Promotes the exchange of Ras-bound GDP by GTP. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Clearly expressed during growth and development. Expression culminates at 8-12 hours of development and is still clearly detectable at 18 hours of development. Belongs to the protein kinase superfamily. TKL Ser/Thr protein kinase family.