Required for proper chemotaxis and phagocytosis; proper spatiotemporal control of F-actin levels in chemotaxing cells. Negative regulator of the PI3K (phosphatidylinositol 3 kinase) pathway. Predominantly phosphorylates serines and threonines and tyrosines at a lower level. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Cells lack polarity, move very slowly, and exhibit an elevated and temporally extended chemoattractant-mediated activation of the kinase Akt/PKB. Belongs to the protein kinase superfamily. TKL Ser/Thr protein kinase family. SH2 domain-containing protein kinase subfamily.