Serine/threonine-protein kinase which is an important downstream effector of CDC42 and plays a role in the regulation of cytoskeleton reorganization and cell migration. Regulates actin cytoskeletal reorganization via phosphorylation of PPP1R12C and MYL9/MLC2. In concert with MYO18A and LRP35A, is involved in modulating lamellar actomyosin retrograde flow that is crucial to cell protrusion and migration. Phosphorylates: PPP1R12A and LIMK2. May play a role in TFRC-mediated iron uptake (By similarity). In concert with FAM89B/LRAP25 mediates the targeting of LIMK1 to the lamellipodium resulting in its activation and subsequent phosphorylation of CFL1 which is important for lamellipodial F-actin regulation (PubMed:25107909). Triggers the formation of an extrusion apical actin ring required for epithelial extrusion of apoptotic cells (By similarity). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Maintained in an inactive, closed conformation by an interaction between the kinase domain and the negative autoregulatory C-terminal coiled-coil region. Agonist binding to the phorbol ester binding site disrupts this, releasing the kinase domain to allow N-terminus-mediated dimerization and kinase activation by transautophosphorylation. Inhibited by chelerythrine chloride (By similarity). Homodimer and homotetramer via the coiled coil regions. Interacts tightly with GTP-bound but not GDP-bound CDC42. Forms a tripartite complex with MYO18A and LRP35A with the latter acting as an adapter connecting CDC42BPA and MYO18A. LRP35A binding results in activation of CDC42BPA by abolition of its negative autoregulation. Interacts with LURAP1 (By similarity). Interacts (via AGC-kinase C-terminal domain) with FAM89B/LRAP25 (via LRR repeat). Forms a tripartite complex with FAM89B/LRAP25 and LIMK1 (PubMed:25107909). Displays a dispersed punctate distribution and concentrates along the cell periphery, especially at the leading edge and cell-cell junction. This concentration is PH-domain dependent (By similarity). Localizes in the lamellipodium in a FAM89B/LRAP25-dependent manner (PubMed:25107909). Proteolytically cleaved by caspases upon apoptosis induction. The cleavage at Asp-478 by CASP3 increases its kinase activity (in vitro). Belongs to the protein kinase superfamily. AGC Ser/Thr protein kinase family. DMPK subfamily.