2015
ChemInform Abstract: Synthesis of Benzopentathiepin Analogues and Their Evaluation as Inhibitors of the Phosphatase STEP.
Baguley T, Nairn A, Lombroso P, Ellman J. ChemInform Abstract: Synthesis of Benzopentathiepin Analogues and Their Evaluation as Inhibitors of the Phosphatase STEP. ChemInform 2015, 46: no-no. DOI: 10.1002/chin.201526245.Peer-Reviewed Original Research
2014
Correction to Substrate-Based Fragment Identification for the Development of Selective, Nonpeptidic Inhibitors of Striatal-Enriched Protein Tyrosine Phosphatase
Baguley T, Xu H, Chatterjee M, Nairn A, Lombroso P, Ellman J. Correction to Substrate-Based Fragment Identification for the Development of Selective, Nonpeptidic Inhibitors of Striatal-Enriched Protein Tyrosine Phosphatase. Journal Of Medicinal Chemistry 2014, 57: 10564-10564. PMCID: PMC4364512, DOI: 10.1021/jm5018847.Peer-Reviewed Original ResearchInhibitor of the Tyrosine Phosphatase STEP Reverses Cognitive Deficits in a Mouse Model of Alzheimer's Disease
Xu J, Chatterjee M, Baguley TD, Brouillette J, Kurup P, Ghosh D, Kanyo J, Zhang Y, Seyb K, Ononenyi C, Foscue E, Anderson GM, Gresack J, Cuny GD, Glicksman MA, Greengard P, Lam TT, Tautz L, Nairn AC, Ellman JA, Lombroso PJ. Inhibitor of the Tyrosine Phosphatase STEP Reverses Cognitive Deficits in a Mouse Model of Alzheimer's Disease. PLOS Biology 2014, 12: e1001923. PMID: 25093460, PMCID: PMC4122355, DOI: 10.1371/journal.pbio.1001923.Peer-Reviewed Original ResearchMeSH KeywordsAlzheimer DiseaseAmino Acid SequenceAnimalsBenzothiepinsCatalytic DomainCell DeathCerebral CortexCognition DisordersCysteineDisease Models, AnimalEnzyme InhibitorsHigh-Throughput Screening AssaysHumansMaleMice, Inbred C57BLMice, KnockoutMolecular Sequence DataNeuronsPhosphorylationPhosphotyrosineProtein Tyrosine Phosphatases, Non-ReceptorSubstrate SpecificityConceptsInhibitors of stepsSpecificity of inhibitorsIsoxazolepropionic acid receptor (AMPAR) traffickingCatalytic cysteinePTP inhibitorsTyrosine phosphataseTyrosine phosphorylationSecondary assaysSTEP KO miceReceptor traffickingFirst large-scale effortN-methyl-D-aspartate receptorsPyk2 activitySTEP inhibitorLarge-scale effortsNovel therapeutic targetSynaptic functionAlzheimer's diseaseNeurodegenerative disordersCortical cellsTherapeutic targetERK1/2Specificity experimentsPhosphataseInhibitors
2013
Substrate-Based Fragment Identification for the Development of Selective, Nonpeptidic Inhibitors of Striatal-Enriched Protein Tyrosine Phosphatase
Baguley TD, Xu HC, Chatterjee M, Nairn AC, Lombroso PJ, Ellman JA. Substrate-Based Fragment Identification for the Development of Selective, Nonpeptidic Inhibitors of Striatal-Enriched Protein Tyrosine Phosphatase. Journal Of Medicinal Chemistry 2013, 56: 7636-7650. PMID: 24083656, PMCID: PMC3875168, DOI: 10.1021/jm401037h.Peer-Reviewed Original ResearchMeSH KeywordsAnimalsBiphenyl CompoundsBlood-Brain BarrierBoronic AcidsCells, CulturedCerebral CortexHumansNeuronsPermeabilityPhosphorous AcidsProtein Tyrosine Phosphatases, Non-ReceptorRatsRats, Sprague-DawleySmall Molecule LibrariesStereoisomerismStructure-Activity RelationshipSubstrate SpecificityConceptsSubstrate Activity ScreeningProtein tyrosine phosphatase activityProtein tyrosine phosphataseTyrosine phosphatase activityGlutamate receptor internalizationOptimization of fragmentsTyrosine phosphataseDual specificityReceptor internalizationDevelopment of SelectiveSTEP inhibitorPhosphatase activityAlzheimer's diseaseIonotropic glutamate receptorsSubstrate-based approachNonpeptidic inhibitorsPotential targetAD mouse modelDrug discoveryRat cortical neuronsActivity screeningCortical neuronsGlutamate receptorsMouse modelNeuropsychiatric disorders
2012
Calpain and STriatal-Enriched protein tyrosine Phosphatase (STEP) activation contribute to extrasynaptic NMDA receptor localization in a Huntington's disease mouse model
Gladding CM, Sepers MD, Xu J, Zhang LY, Milnerwood AJ, Lombroso PJ, Raymond LA. Calpain and STriatal-Enriched protein tyrosine Phosphatase (STEP) activation contribute to extrasynaptic NMDA receptor localization in a Huntington's disease mouse model. Human Molecular Genetics 2012, 21: 3739-3752. PMID: 22523092, PMCID: PMC3412376, DOI: 10.1093/hmg/dds154.Peer-Reviewed Original ResearchMeSH KeywordsAnimalsCalpainCoculture TechniquesDisease Models, AnimalEnzyme ActivationEnzyme InhibitorsHuntington DiseaseIon Channel GatingMiceModels, BiologicalNeostriatumNeuronsPhosphorylationPhosphotyrosineProtein TransportProtein Tyrosine Phosphatases, Non-ReceptorReceptors, N-Methyl-D-AspartateSynapsesConceptsYAC128 striatumProtein tyrosine phosphatase activationNMDAR localizationCalpain cleavageProtein tyrosine phosphataseTyrosine phosphatase activationEarly synaptic defectsWhole-cell NMDAR currentsDisease mouse modelGluN2B expressionNMDA receptor traffickingMutant huntingtin proteinCalpain inhibitionTyrosine phosphataseHuntington's diseaseFull-length mhttPlasma membranePhosphatase activationC-terminusReceptor traffickingNMDAR traffickingPolyglutamine repeatsMouse modelHuntingtin proteinNMDA receptor localizationGenetic manipulation of STEP reverses behavioral abnormalities in a fragile X syndrome mouse model
Goebel‐Goody S, Wilson‐Wallis E, Royston S, Tagliatela S, Naegele J, Lombroso P. Genetic manipulation of STEP reverses behavioral abnormalities in a fragile X syndrome mouse model. Genes Brain & Behavior 2012, 11: 586-600. PMID: 22405502, PMCID: PMC3922131, DOI: 10.1111/j.1601-183x.2012.00781.x.Peer-Reviewed Original ResearchConceptsFragile X syndromeFragile X syndrome mouse modelProtein tyrosine phosphataseMental retardation proteinMRNAs downstreamControl translationTyrosine phosphataseGenetic manipulationGenetic basisFMR1 geneLoss of stepsX syndromeSyndrome mouse modelFMRPReceptor activationGlutamate receptor activationExcess levelsSynaptic strengthSynaptic strengtheningBasal levelsC-Fos activationActivationTranscriptionFynMouse modelInhibition of Hematopoietic Protein Tyrosine Phosphatase Augments and Prolongs ERK1/2 and p38 Activation
Tautz L, Sergienko E, Xu J, Liu W, Dahl R, Critton D, Su Y, Brown B, Chan X, Yang L, Bobkova E, Vasile S, Yuan H, Rascon J, Colayco S, Sidique S, Cosford N, Chung T, Mustelin T, Page R, Lombroso P. Inhibition of Hematopoietic Protein Tyrosine Phosphatase Augments and Prolongs ERK1/2 and p38 Activation. The FASEB Journal 2012, 26: 766.12-766.12. DOI: 10.1096/fasebj.26.1_supplement.766.12.Peer-Reviewed Original ResearchHematopoietic protein tyrosine phosphataseP38 activationProtein tyrosine phosphataseUnique amino acid residuesAmino acid residuesNew drug targetsCell cycle arrestMAP kinases ERK1/2Activation of ERK1/2Tyrosine phosphataseHePTPMutagenesis experimentsMAP kinaseKinases ERK1/2Acid residuesCatalytic pocketDrug targetsTransient activationCycle arrestT-cell acute lymphoblastic leukemiaERK1/2Prolonged activationHuman T cellsPharmacological inhibitionCancer cells
2011
Therapeutic Implications for Striatal-Enriched Protein Tyrosine Phosphatase (STEP) in Neuropsychiatric Disorders
Goebel-Goody SM, Baum M, Paspalas CD, Fernandez SM, Carty NC, Kurup P, Lombroso PJ. Therapeutic Implications for Striatal-Enriched Protein Tyrosine Phosphatase (STEP) in Neuropsychiatric Disorders. Pharmacological Reviews 2011, 64: 65-87. PMID: 22090472, PMCID: PMC3250079, DOI: 10.1124/pr.110.003053.Peer-Reviewed Original ResearchConceptsStriatal-enriched protein tyrosine phosphataseProtein tyrosine phosphataseTyrosine phosphataseStress-activated protein kinase p38Extracellular regulated kinases 1Brain-specific phosphataseSrc family tyrosine kinase FynProtein kinase p38Tyrosine kinase FynN-methyl-D-aspartate receptorsFragile X syndromeDephosphorylation of ERK1/2Stroke/ischemiaSurface NMDARsKinase FynAlcohol-induced memory lossDiverse neuropsychiatric disordersLocal translationKinase 1Kinase p38STEP expressionX syndromeNeuronal functionDephosphorylationFunction contributesStriatal-Enriched Protein Tyrosine Phosphatase Expression and Activity in Huntington's Disease: A STEP in the Resistance to Excitotoxicity
Saavedra A, Giralt A, Rué L, Xifró X, Xu J, Ortega Z, Lucas JJ, Lombroso PJ, Alberch J, Pérez-Navarro E. Striatal-Enriched Protein Tyrosine Phosphatase Expression and Activity in Huntington's Disease: A STEP in the Resistance to Excitotoxicity. Journal Of Neuroscience 2011, 31: 8150-8162. PMID: 21632937, PMCID: PMC3472648, DOI: 10.1523/jneurosci.3446-10.2011.Peer-Reviewed Original ResearchMeSH KeywordsAnimalsBrainCalcineurinCell DeathDisease Models, AnimalGene Expression RegulationGene Products, tatHuntingtin ProteinHuntington DiseaseMiceMice, Neurologic MutantsMice, TransgenicMicroinjectionsNerve Tissue ProteinsNuclear ProteinsPhosphorylationProtein Tyrosine Phosphatases, Non-ReceptorQuinolinic AcidSignal TransductionConceptsStriatal-enriched protein tyrosine phosphataseCell deathSTEP expressionPhosphorylation levelsProtein Tyrosine Phosphatase ExpressionProtein tyrosine phosphataseSTEP phosphorylationTyrosine phosphataseProtein kinasePhosphorylated ERK2Phosphatase expressionHuntington's diseaseSTEP proteinMutant huntingtinCalcineurin activityPhosphorylationExon 1STEP protein levelsDisease mouse modelProtein levelsMouse modelMouse striatumTAT-STEPHuntington's disease mouse modelExpressionStriatal‐enriched protein tyrosine phosphatase (STEP) knockout mice have enhanced hippocampal memory
Venkitaramani DV, Moura PJ, Picciotto MR, Lombroso PJ. Striatal‐enriched protein tyrosine phosphatase (STEP) knockout mice have enhanced hippocampal memory. European Journal Of Neuroscience 2011, 33: 2288-2298. PMID: 21501258, PMCID: PMC3118976, DOI: 10.1111/j.1460-9568.2011.07687.x.Peer-Reviewed Original ResearchMeSH KeywordsAnimalsBehavior, AnimalFocal Adhesion Kinase 2HippocampusMemoryMiceMice, Inbred C57BLMice, KnockoutMitogen-Activated Protein Kinase 1Mitogen-Activated Protein Kinase 3PhosphorylationProtein Tyrosine Phosphatases, Non-ReceptorReceptors, AMPAReceptors, N-Methyl-D-AspartateSynaptic TransmissionConceptsStriatal-enriched protein tyrosine phosphataseSTEP KO miceProtein tyrosine phosphataseBrain-specific phosphataseProline-rich tyrosine kinaseEffect of deletionN-methyl-D-aspartate receptorsERK1/2 substratesNR1/NR2B N‐Methyl‐d‐Aspartate ReceptorsPotential molecular mechanismsTyrosine phosphataseSignaling proteinsTyrosine phosphorylationDownstream effectorsKinase 1/2Molecular mechanismsTyrosine kinaseFunctional importanceKnockout micePhosphorylationSTEP knockout miceSynaptic strengtheningIsoxazole propionic acid (AMPA) receptorsSynaptosomal expressionRegulation
2010
Genetic reduction of striatal-enriched tyrosine phosphatase (STEP) reverses cognitive and cellular deficits in an Alzheimer’s disease mouse model
Zhang Y, Kurup P, Xu J, Carty N, Fernandez SM, Nygaard HB, Pittenger C, Greengard P, Strittmatter SM, Nairn AC, Lombroso PJ. Genetic reduction of striatal-enriched tyrosine phosphatase (STEP) reverses cognitive and cellular deficits in an Alzheimer’s disease mouse model. Proceedings Of The National Academy Of Sciences Of The United States Of America 2010, 107: 19014-19019. PMID: 20956308, PMCID: PMC2973892, DOI: 10.1073/pnas.1013543107.Peer-Reviewed Original ResearchConceptsStriatal-enriched tyrosine phosphataseTyrosine phosphataseDisease mouse modelStriatal-enriched phosphataseAlzheimer's diseaseCellular deficitsGenetic manipulationNMDA receptorsMouse modelTriple transgenic AD mouse modelIncurable neurodegenerative disorderTransgenic AD mouse modelAlzheimer's disease mouse modelPathophysiology of ADSTEP inhibitorGenetic reductionAD mouse modelHuman AD patientsSoluble Aβ oligomersSynaptic functionPhosphataseNeurodegenerative disordersAD patientsDevastating disorderAnimal models
2009
Extrasynaptic NMDA Receptors Couple Preferentially to Excitotoxicity via Calpain-Mediated Cleavage of STEP
Xu J, Kurup P, Zhang Y, Goebel-Goody SM, Wu PH, Hawasli AH, Baum ML, Bibb JA, Lombroso PJ. Extrasynaptic NMDA Receptors Couple Preferentially to Excitotoxicity via Calpain-Mediated Cleavage of STEP. Journal Of Neuroscience 2009, 29: 9330-9343. PMID: 19625523, PMCID: PMC2737362, DOI: 10.1523/jneurosci.2212-09.2009.Peer-Reviewed Original ResearchMeSH KeywordsAlternative SplicingAnimalsBrainCalpainCell DeathCells, CulturedCyclin-Dependent Kinase 5EndocytosisGlutamic AcidIn Vitro TechniquesMiceMice, KnockoutMitogen-Activated Protein Kinase 1Mitogen-Activated Protein Kinase 3NeuronsP38 Mitogen-Activated Protein KinasesProtein Tyrosine Phosphatases, Non-ReceptorRatsRats, Sprague-DawleyReceptors, N-Methyl-D-AspartateSynapsesConceptsStriatal-enriched protein tyrosine phosphataseCalpain cleavage sitesP38 activationCell deathCleavage siteExtracellular signal-regulated kinase 1/2Protein tyrosine phosphataseSignal-regulated kinase 1/2Promotes cell survivalActivation of p38Tyrosine phosphataseSubstrate bindingKinase 1/2ERK1/2 activationCalpain cleavageCell survivalNovel mechanismCalpain-mediated proteolysisReceptors coupleP38NMDAR stimulationPostsynaptic terminalsValid targetCleavage productsSTEP substrates
2008
The Tyrosine Phosphatase STEP Mediates AMPA Receptor Endocytosis after Metabotropic Glutamate Receptor Stimulation
Zhang Y, Venkitaramani DV, Gladding CM, Zhang Y, Kurup P, Molnar E, Collingridge GL, Lombroso PJ. The Tyrosine Phosphatase STEP Mediates AMPA Receptor Endocytosis after Metabotropic Glutamate Receptor Stimulation. Journal Of Neuroscience 2008, 28: 10561-10566. PMID: 18923032, PMCID: PMC2586105, DOI: 10.1523/jneurosci.2666-08.2008.Peer-Reviewed Original ResearchConceptsStriatal-enriched protein tyrosine phosphataseProtein tyrosine phosphataseTyrosine phosphataseAMPAR internalizationMitogen-activated protein kinasePhosphoinositide-3-kinase (PI3K) pathwayAMPA receptor endocytosisTyrosine dephosphorylationAMPA receptor traffickingReceptor endocytosisProtein kinaseKinase pathwayStimulation of mGluR5Receptor traffickingNMDAR endocytosisAMPAR traffickingEndocytosisMetabotropic glutamate receptor stimulationTraffickingSurface expressionInternalizationGlutamate receptor stimulationSynaptic plasticityCentral eventPhosphatase
2007
Status Epilepticus-Induced Somatostatinergic Hilar Interneuron Degeneration Is Regulated by Striatal Enriched Protein Tyrosine Phosphatase
Choi YS, Lin SL, Lee B, Kurup P, Cho HY, Naegele JR, Lombroso PJ, Obrietan K. Status Epilepticus-Induced Somatostatinergic Hilar Interneuron Degeneration Is Regulated by Striatal Enriched Protein Tyrosine Phosphatase. Journal Of Neuroscience 2007, 27: 2999-3009. PMID: 17360923, PMCID: PMC2701360, DOI: 10.1523/jneurosci.4913-06.2007.Peer-Reviewed Original ResearchConceptsStriatal-enriched protein tyrosine phosphataseERK/MAPK activationProtein tyrosine phosphataseCell deathTyrosine phosphataseExtracellular signal-regulated kinase/mitogen-activated protein kinase pathwayKinase/mitogen-activated protein kinase pathwayMAPK activationMAPK pathwayERK/MAPK signalingMitogen-activated protein kinase pathwayStriatal enriched protein tyrosine phosphataseProtein kinase pathwayNeuroprotective responseKinase pathwayImmediate early gene expressionKey regulatorMAPK signalingGene expressionMolecular mechanismsVivo disruptionSignificant rescuePathwayPhosphataseActivation
2006
The Striatal-Enriched Protein Tyrosine Phosphatase Gates Long-Term Potentiation and Fear Memory in the Lateral Amygdala
Paul S, Olausson P, Venkitaramani DV, Ruchkina I, Moran TD, Tronson N, Mills E, Hakim S, Salter MW, Taylor JR, Lombroso PJ. The Striatal-Enriched Protein Tyrosine Phosphatase Gates Long-Term Potentiation and Fear Memory in the Lateral Amygdala. Biological Psychiatry 2006, 61: 1049-1061. PMID: 17081505, PMCID: PMC1853327, DOI: 10.1016/j.biopsych.2006.08.005.Peer-Reviewed Original ResearchMeSH KeywordsAcoustic StimulationAminoacetonitrileAmygdalaAnimalsBehavior, AnimalCells, CulturedConditioning, ClassicalCycloheximideElectric StimulationEnzyme InhibitorsFearFemaleImmunohistochemistryIn Vitro TechniquesLong-Term PotentiationMemoryMitogen-Activated Protein Kinase 1Mitogen-Activated Protein Kinase 3NeostriatumPatch-Clamp TechniquesPoint MutationPregnancyProtein Synthesis InhibitorsProtein Tyrosine PhosphatasesRatsRats, Sprague-DawleyTranslocation, GeneticConceptsStriatal-enriched protein tyrosine phosphataseERK1/2 activationMitogen-activated protein kinaseProtein tyrosine phosphataseDe novo translationActivation of ERK1/2Tyrosine phosphataseProtein bindsKinase signalingProtein kinaseSequential recruitmentAmygdala-dependent memory formationERK pathwayMemory formationPrimary cell culturesNuclear translocationBiphasic activationLong-term potentiationTranslation blockTAT-STEPERKCell culturesERK1/2ActivationPathwaySynaptic plasticity: one STEP at a time
Braithwaite SP, Paul S, Nairn AC, Lombroso PJ. Synaptic plasticity: one STEP at a time. Trends In Neurosciences 2006, 29: 452-458. PMID: 16806510, PMCID: PMC1630769, DOI: 10.1016/j.tins.2006.06.007.Peer-Reviewed Original Research
1997
STEP: a family of brain-enriched PTPs. Alternative splicing produces transmembrane, cytosolic and truncated isoforms.
Bult A, Zhao F, Dirkx R, Raghunathan A, Solimena M, Lombroso P. STEP: a family of brain-enriched PTPs. Alternative splicing produces transmembrane, cytosolic and truncated isoforms. European Journal Of Cell Biology 1997, 72: 337-44. PMID: 9127733.Peer-Reviewed Original ResearchMeSH KeywordsAlternative SplicingAmino Acid SequenceAnimalsBase SequenceBlotting, NorthernBlotting, WesternBrainCalcium-Binding ProteinsCalnexinCHO CellsCricetinaeFemaleFluorescent Antibody Technique, IndirectMembrane ProteinsMolecular Sequence DataProtein Tyrosine PhosphatasesProtein Tyrosine Phosphatases, Non-ReceptorRatsSynaptophysinTransfectionConceptsProtein tyrosine phosphataseCatalytic phosphatase domainProtein tyrosine kinase familyHydrophobic amino acid sequenceAlternative splicing mechanismAmino acid sequencePrevious biochemical studiesTyrosine kinase familyStop codon upstreamPhosphatase domainCytosolic variantAlternative splicingMembrane compartmentsTyrosine phosphataseKinase familySplicing mechanismSubcellular localizationCytosolic proteinsAcid sequenceN-terminusInactive variantContinuous sucrose gradientSTEP isoformsPolyproline domainEndoplasmic reticulum
1995
Molecular Cloning of the Human Homolog of a Striatum-Enriched Phosphatase (STEP) Gene and Chromosomal Mapping of the Human and Murine Loci
Li X, Luna J, Lombroso P, Francke U. Molecular Cloning of the Human Homolog of a Striatum-Enriched Phosphatase (STEP) Gene and Chromosomal Mapping of the Human and Murine Loci. Genomics 1995, 28: 442-449. PMID: 7490079, DOI: 10.1006/geno.1995.1173.Peer-Reviewed Original ResearchConceptsSrc homology domain 3STEP geneTyrosine phosphataseSomatic cell hybrid analysisHuman fetal brain cDNA libraryFetal brain cDNA libraryPhosphatase catalytic domainCell hybrid analysisProtein tyrosine phosphataseAmino acid domainProline-rich regionCandidate disease genesBrain cDNA libraryUsher syndrome type 1CAmino acid levelsChromosomal mappingPhosphatase geneMutant lociHuman homologTrue homologsMolecular cloningCatalytic domainAcid domainMurine locusCDNA libraryIdentification of two alternatively spliced transcripts of STEP: a subfamily of brain-enriched protein tyrosine phosphatases
Sharma E, Zhao F, Bult A, Lombroso P. Identification of two alternatively spliced transcripts of STEP: a subfamily of brain-enriched protein tyrosine phosphatases. Brain Research 1995, 32: 87-93. PMID: 7494467, DOI: 10.1016/0169-328x(95)00066-2.Peer-Reviewed Original ResearchConceptsTyrosine phosphatase domainPhosphatase domainProtein tyrosineSpliced transcriptsExon-intron organizationProtein tyrosine phosphataseOpen reading frameTyrosine phosphataseReading frameDistinct functionsGenomic DNANorthern analysisSTEP geneSTEP isoformsMolecular massTranscriptsSTEP61ProteinMouse brainTyrosineCentral nervous systemSubfamiliesGenesNervous systemMonoclonal antibodiesA Neuronal Protein Tyrosine Phosphatase Induced by Nerve Growth Factor (∗)
Sharma E, Lombroso P. A Neuronal Protein Tyrosine Phosphatase Induced by Nerve Growth Factor (∗). Journal Of Biological Chemistry 1995, 270: 49-53. PMID: 7814416, DOI: 10.1074/jbc.270.1.49.Peer-Reviewed Original ResearchMeSH KeywordsAmino Acid SequenceAnimalsBase SequenceDNAEnzyme InductionIntracellular Signaling Peptides and ProteinsMolecular Sequence DataNerve Growth FactorsNerve Tissue ProteinsNeuronsPC12 CellsProtein Tyrosine PhosphatasesRatsReceptor-Like Protein Tyrosine Phosphatases, Class 7Recombinant Fusion ProteinsSequence Homology, Amino AcidConceptsNerve growth factorNGF treatmentGrowth factorNon-receptor protein tyrosine phosphataseRat brainNeuronal growthProtein tyrosine phosphataseMRNA levelsBrainNorthern blot analysisPC12 cellsBlot analysisTyrosine phosphataseTreatmentPhosphataseExpressionFusion proteinTyrosine phosphatase activity