Interferes with CBL-mediated down-regulation and degradation of receptor-type tyrosine kinases. Promotes accumulation of activated target receptors, such as T-cell receptors and EGFR, on the cell surface. Exhibits tyrosine phosphatase activity toward several substrates including EGFR, FAK, SYK, and ZAP70. Down-regulates proteins that are dually modified by both protein tyrosine phosphorylation and ubiquitination. H2O + O-phospho-L-tyrosyl-[protein] = L-tyrosyl-[protein] + phosphate Homodimer (PubMed:20516590, PubMed:17679096). Interacts with JAK2 (in vitro) (PubMed:12370296). Interacts with CBL. Part of a complex containing CBL and activated EGFR. Interacts with ubiquitin and with mono-ubiquitinated proteins (By similarity). Interacts with ZAP70 (ubiquitinated form) (PubMed:26903241). Detected in splenic T-cells and B-cells, total spleen, skeletal muscle, heart, lung, kidney, thymus, brain and liver (at protein level). Highly expressed in brain. Detected in heart, spleen, lung, liver, kidney and testis. Mice display strikingly elevated levels of tyrosine phosphorylated, ubiquitinated proteins following TCR stimulation. They are prothrombotic and have shorter bleeding times, which is attributed to insufficient SYK dephosphorylation in platelets.