CRYSTAL STRUCTURE OF HEPTP IN COMPLEX WITH A MONOPHOSPHORYLATED ERK2 PEPTIDE 3D42 HYDROLASE, HEPTP, HUMAN HEMATOPOIETIC TYROSINE PHOSPHATASE CATALYTIC DOMAIN MUTANT, LC-PTP, PTPN7, ERK2, PTP-PEPTIDE COMPLEX, MAPK-DERIVED PEPTIDE, ALTERNATIVE SPLICING, CYTOPLASM, PHOSPHOPROTEIN, PROTEIN PHOSPHATASE, ACETYLATION, ATP-BINDING, CELL CYCLE, HOST-VIRUS INTERACTION, KINASE, NUCLEOTIDE-BINDING, SERINE/THREONINE-PROTEIN KINASE, TRANSFERASE