Serine/threonine kinase involved in various developmental processes (PubMed:9601646, PubMed:10587646, PubMed:10962553, PubMed:11740943, PubMed:12172554, PubMed:11872800, PubMed:14525946, PubMed:12893776, PubMed:15466161, PubMed:15712201). During early embryogenesis, acts as a survival protein (PubMed:9601646, PubMed:10962553). During mid-embryogenesis, phosphorylates and activates trh, a transcription factor required for tracheal cell fate determination (PubMed:11740943). Also regulates tracheal cell migration (PubMed:11740943, PubMed:14525946). Later in development, acts downstream of PI3K and Pk61C/PDK1 in the insulin receptor transduction pathway which regulates cell growth and organ size, by phosphorylating and antagonizing FOXO transcription factor (PubMed:10587646, PubMed:10962553, PubMed:11752451, PubMed:12893776, PubMed:25329475, PubMed:29025897, PubMed:24603715). Controls follicle cell size during oogenesis (PubMed:15712201). May also stimulate cell growth by phosphorylating Gig/Tsc2 and inactivating the Tsc complex (PubMed:12172554, PubMed:15466161). Dephosphorylation of 'Ser-586' by Phlpp triggers apoptosis and suppression of tumor growth (PubMed:10962553). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with trbl. Recruited to plasma membrane upon activation. Ubiquitously expressed. Present in ovary, where it is concentrated at the basal side of follicle cells. Expressed both maternally and zygotically. Strongly expressed in embryo and pupa. Weakly expressed in larva. Mildly expressed in adult. Binding of the PH domain to the phosphatidylinositol 3-kinase alpha (PI(3)K) results in its targeting to the plasma membrane. Phosphorylated and activated by Pk61C/PDK1 (PubMed:11344272). Phosphorylated on Ser-586 by the TORC2 complex (PubMed:10962553, PubMed:15718470, PubMed:22493059). Death at the first instar larval stage (PubMed:9601646). Conditional RNAi-mediated knockdown in the female germline reduces ovary size (PubMed:24786828). RNAi-mediated knockdown in both larval salivary glands and fat body, results in small salivary glands displaying ectopic lipid storage and reduced expression of CdsA (PubMed:24603715). Major form. Belongs to the protein kinase superfamily. AGC Ser/Thr protein kinase family. RAC subfamily.