Promotes the exchange of GDP by GTP. Together with leukocyte antigen-related (LAR) protein, it could play a role in coordinating cell-matrix and cytoskeletal rearrangements necessary for cell migration and cell growth (By similarity). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] The N-terminal DBL/GEF domain specifically catalyzes nucleotide exchange for RAC1, leading to the activation of Jun kinase and the production of membrane ruffles. The second DBL/GEF domain is an exchange factor for rhoa and induces the formation of stress fibers (By similarity). Phosphorylated on serine residue(s). Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family.