Non-receptor protein-tyrosine kinase that regulates reorganization of the actin cytoskeleton, cell polarization, cell migration, adhesion, spreading and bone remodeling. Plays a role in the regulation of the humoral immune response, and is required for normal levels of marginal B-cells in the spleen and normal migration of splenic B-cells. Required for normal macrophage polarization and migration towards sites of inflammation. Regulates cytoskeleton rearrangement and cell spreading in T-cells, and contributes to the regulation of T-cell responses. Promotes osteoclastic bone resorption; this requires both PTK2B/PYK2 and SRC. May inhibit differentiation and activity of osteoprogenitor cells. Functions in signaling downstream of integrin and collagen receptors, immune receptors, G protein-coupled receptors (GPCR), cytokine, chemokine and growth factor receptors, and mediates responses to cellular stress. Forms multisubunit signaling complexes with SRC and SRC family members upon activation; this leads to the phosphorylation of additional tyrosine residues, creating binding sites for scaffold proteins, effectors and substrates. Regulates numerous signaling pathways. Promotes activation of phosphatidylinositol 3-kinase and of the AKT1 signaling cascade. Promotes activation of NOS3. Regulates production of the cellular messenger cGMP. Promotes activation of the MAP kinase signaling cascade, including activation of MAPK1/ERK2, MAPK3/ERK1 and MAPK8/JNK1. Promotes activation of Rho family GTPases, such as RHOA and RAC1. Recruits the ubiquitin ligase MDM2 to P53/TP53 in the nucleus, and thereby regulates P53/TP53 activity, P53/TP53 ubiquitination and proteasomal degradation. Acts as a scaffold, binding to both PDPK1 and SRC, thereby allowing SRC to phosphorylate PDPK1 at 'Tyr-9, 'Tyr-373', and 'Tyr-376'. Promotes phosphorylation of NMDA receptors by SRC family members, and thereby contributes to the regulation of NMDA receptor ion channel activity and intracellular Ca(2+) levels. May also regulate potassium ion transport by phosphorylation of potassium channel subunits. Phosphorylates SRC; this increases SRC kinase activity. Phosphorylates ASAP1, NPHP1, KCNA2 and SHC1. Promotes phosphorylation of ASAP2, RHOU and PXN; this requires both SRC and PTK2/PYK2. {ECO:0000269|PubMed:10022920, ECO:0000269|PubMed:12771146, ECO:0000269|PubMed:12893833, ECO:0000269|PubMed:14585963, ECO:0000269|PubMed:15050747, ECO:0000269|PubMed:15166227, ECO:0000269|PubMed:17634955, ECO:0000269|PubMed:18086875, ECO:0000269|PubMed:18339875, ECO:0000269|PubMed:18587400, ECO:0000269|PubMed:18765415, ECO:0000269|PubMed:19086031, ECO:0000269|PubMed:19207108, ECO:0000269|PubMed:19244237, ECO:0000269|PubMed:19428251, ECO:0000269|PubMed:19648005, ECO:0000269|PubMed:19880522, ECO:0000269|PubMed:20001213, ECO:0000269|PubMed:20381867, ECO:0000269|PubMed:20521079, ECO:0000269|PubMed:21357692, ECO:0000269|PubMed:21533080, ECO:0000269|PubMed:7544443, ECO:0000269|PubMed:8670418, ECO:0000269|PubMed:8849729}. This is the function of Ensembl gene identifier ENSG00000120899 (PTK2B, protein tyrosine kinase 2 beta).