Catalytically inactive protein kinase that acts as a scaffold protein (PubMed:29503074). Functions as an effector of the small GTPase RND2, which stimulates RhoA activity and inhibits NGF-induced neurite outgrowth (PubMed:16481321). Promotes Src family kinase (SFK) signallig by regulating the subcellular localization of CSK, a negative regulator of these kinases, leading to the regulation of cell morphology and motility by a CSK-dependent mechanism (PubMed:27116701, PubMed:21873224). Acts as a critical coactivator of Notch signaling (By similarity). Homodimer (PubMed:29503074). Dimerization leads to the catalytic activation of CSK (PubMed:29503074). Interacts (via C-terminus) with RND2 (PubMed:16481321). Interacts with CSK (via SH2 domain) in a Tyr-391 phosphorylation-dependent manner; this interaction potentiates kinase activity of CSK (PubMed:29503074, PubMed:21873224, PubMed:27116701). Interacts with NOTCH1 intracellular domain (N1ICD) (By similarity). Forms a complex with N1ICD and MAML1, in a MAML1-dependent manner (By similarity). Colocalized with NOTCH1 in the nucleus. Highly-expressed in brain, including cortical and hippocampal pyramidal neurons, as well as in kidney, spleen, colon and small intestine (PubMed:16481321). The dimerization region encompasses helices both from the N- and C-terminal of the protein kinase domain. Phosphorylated by CSK on Tyr-238, Tyr-343, and Tyr-391; Tyr-391 is a primary site of phosphorylation. Belongs to the protein kinase superfamily. Despite of the presence of a putative ATP-binding motif, this protein does not bind ATP, suggesting that it has no protein kinase activity (PubMed:29503074).