Non-receptor tyrosine-protein kinase found in hematopoietic cells that transmits signals from cell surface receptors and plays an important role in the regulation of innate immune responses, including neutrophil, monocyte, macrophage and mast cell functions, phagocytosis, cell survival and proliferation, cell adhesion and migration. Acts downstream of receptors that bind the Fc region of immunoglobulins, such as FCGR1A and FCGR2A, but also CSF3R, PLAUR, the receptors for IFNG, IL2, IL6 and IL8, and integrins, such as ITGB1 and ITGB2. During the phagocytic process, mediates mobilization of secretory lysosomes, degranulation, and activation of NADPH oxidase to bring about the respiratory burst. Plays a role in the release of inflammatory molecules. Promotes reorganization of the actin cytoskeleton and actin polymerization, formation of podosomes and cell protrusions. Inhibits TP73-mediated transcription activation and TP73-mediated apoptosis. Phosphorylates CBL in response to activation of immunoglobulin gamma Fc region receptors. Phosphorylates ADAM15, BCR, ELMO1, FCGR2A, GAB1, GAB2, RAPGEF1, STAT5B, TP73, VAV1 and WAS (By similarity). ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Subject to autoinhibition, mediated by intramolecular interactions involving the SH2 and SH3 domains. Kinase activity is also regulated by phosphorylation at regulatory tyrosine residues. Phosphorylation at Tyr-409 is required for optimal activity. Phosphorylation at Tyr-520 inhibits kinase activity (By similarity). Interacts with ADAM15. Interacts with FASLG. Interacts with ARRB1 and ARRB2. Interacts with FCGR1A; the interaction may be indirect. Interacts with IL6ST. Interacts (via SH3 domain) with ELMO1. Interacts (via SH3 domain) with TP73. Interacts with YAP1. Interacts with ABL1 and ITGB1, and thereby recruits ABL1 to activated ITGB1. Interacts (via SH2 domain) with FLT3 (tyrosine phosphorylated). Interacts with CBL. Interacts with VAV1, WAS and RAPGEF1.Interacts (via SH3 domain) with WDCP. Associated with specialized secretory lysosomes called azurophil granules. A fraction of this isoform is found in the cytoplasm, some of this fraction is myristoylated (By similarity). A small fraction of this isoform is associated with caveolae. Localization at the cell membrane and at caveolae requires palmitoylation at Cys-3. Colocalizes with the actin cytoskeleton at focal adhesions (By similarity). Expressed strongly in spleen and at very low levels in thymus. Phosphorylated on several tyrosine residues. Autophosphorylated. Becomes rapidly phosphorylated upon activation of the immunoglobulin receptors FCGR1A and FCGR2A. Phosphorylation at Tyr-409 increases kinase activity. Phosphorylation at Tyr-520 inhibits kinase activity. Kinase activity is not required for phosphorylation at Tyr-520, suggesting that this site may be a target of other kinases (By similarity). Ubiquitinated by CBL, leading to its degradation via the proteasome. Isoform 2 palmitoylation at position 2 requires prior myristoylation. Palmitoylation at position 3 is required for caveolar localization of isoform 2. Belongs to the protein kinase superfamily. Tyr protein kinase family. SRC subfamily. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus.