Couples tyrosine kinase signals with the activation of the Rho/Rac GTPases, thus leading to cell differentiation and/or proliferation. Interacts with SHB (By similarity). Interacts with APS, DOCK2, GRB2, GRB3, DOCK2, SLA, TEC and ZNF655/VIK. Interacts with SIAH2; without leading to its degradation. Associates with BLNK, PLCG1, GRB2 and NCK1 in a B-cell antigen receptor-dependent fashion. Interacts with CBLB; which inhibits tyrosine phosphorylation and down-regulates activity (PubMed:10646609, PubMed:10646608). May interact with CCPG1 (PubMed:17000758). Interacts with CLNK (PubMed:11463797). Interacts with THEMIS2 (PubMed:20644716). Interacts with NEK3 and this interaction is prolactin-dependent. Interacts with ITK. Interacts with PTK2B/PYK2 (By similarity). Interacts with HCK. Interacts with PTK2B/PYK2. Interacts (via SH2 domain) with SYK (By similarity). Interacts with ANKRD54 (PubMed:19064729). Interacts with CD6 (PubMed:24584089). Interacts with isoform 2 of CRACR2A (By similarity). Widely expressed in hematopoietic cells but not in other cell types. Found in the spleen and lung. The DH domain is involved in interaction with CCPG1. Phosphorylated by FYN (By similarity). Phosphorylated on tyrosine residues by HCK in response to IFNG and bacterial lipopolysaccharide (LPS).