Tyrosine phosphatase which dephosphorylates or contributes to the dephosphorylation of CTNND1, FLT3, PDGFRB, MET, RET (variant MEN2A), KDR, LYN, SRC, MAPK1, MAPK3, EGFR, TJP1, OCLN, PIK3R1 and PIK3R2. Plays a role in cell adhesion, migration, proliferation and differentiation. Involved in vascular development. Regulator of macrophage adhesion and spreading. Positively affects cell-matrix adhesion. Positive regulator of platelet activation and thrombosis. Negative regulator of cell proliferation. Negative regulator of PDGF-stimulated cell migration; through dephosphorylation of PDGFR. Positive regulator of endothelial cell survival, as well as of VEGF-induced SRC and AKT activation; through KDR dephosphorylation. Negative regulator of EGFR signaling pathway; through EGFR dephosphorylation. Enhances the barrier function of epithelial junctions during reassembly. Negatively regulates T-cell receptor (TCR) signaling. Upon T-cell TCR activation, it is up-regulated and excluded from the immunological synapses, while upon T-cell-antigen presenting cells (APC) disengagement, it is no longer excluded and can dephosphorylate PLCG1 and LAT to down-regulate prolongation of signaling. H2O + O-phospho-L-tyrosyl-[protein] = L-tyrosyl-[protein] + phosphate Monomer. Interacts with CTNNB1 (phosphorylated) and JUP (phosphorylated). Interacts with FLT3 (phosphorylated). Interacts with GAB1 and GRB2. After T-cell stimulation, it is temporarily excluded from immunological synapses. Isoform 1 and isoform 3 result from alternative initiation of translation within the same 5' exon but produce the same functional protein following cleavage of their respective signal peptides (PubMed:18603590). Alternative initiation is probably a conserved mechanism in mammals to regulate the overall expression of that functional protein (PubMed:18603590, PubMed:33296397). Expressed in the promyelocytic cell line HL-60, the granulocyte-macrophage colony-stimulating factor-dependent leukemic cell line F-36P, and the IL3 and erythropoietin-dependent leukemic cell line F-36E. Expressed predominantly in epithelial cells and lymphocytes. Enhanced expression at high cell density. N- and O-glycosylated. Belongs to the protein-tyrosine phosphatase family. Receptor class 3 subfamily.