Catalytically inactive protein kinase that acts as a scaffold protein (By similarity). Functions as an effector of the small GTPase RND2, which stimulates RhoA activity and inhibits NGF-induced neurite outgrowth (By similarity). Promotes Src family kinase (SFK) signaling 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 (By similarity). Acts as a critical coactivator of Notch signaling (PubMed:25038227). Homodimer (By similarity). Dimerization leads to the catalytic activation of CSK (By similarity). Interacts (via C-terminus) with RND2 (By similarity). Interacts with CSK (via SH2 domain) in a Tyr-391 phosphorylation-dependent manner; this interaction potentiates kinase activity of CSK (By similarity). Interacts with NOTCH1 intracellular domain (N1ICD) (PubMed:25038227). Forms a complex with PRAG1, N1ICD and MAML1, in a MAML1-dependent manner (PubMed:25038227). Colocalized with NOTCH1 in the nucleus (PubMed:25038227). 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. Deficient mice shown complete embryonic lethality (PubMed:25038227). 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. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus.