ATP + L-seryl-[tau protein] = ADP + H(+) + O-phospho-L-seryl-[tau protein] ATP + L-threonyl-[tau protein] = ADP + H(+) + O-phospho-L-threonyl-[tau protein] Inhibited by cyclin kinase 2 (CDK2) inhibitors, including GW8510. Was identified as a drug target for the treatment of African sleeping sickness. RNA interference leads to growth arrest and altered parasite morphology, demonstrating requirement for cell survival. Belongs to the protein kinase superfamily. CMGC Ser/Thr protein kinase family. GSK-3 subfamily.