DAG-regulated serine-threonine kinases in T cells. TCR triggering activates PLC-γ, which cleaves PtdIns(4,5)P2 to generate two key second messenger molecules, DAG and Ins(1,4,5)P3. The accumulation of DAG in the plasma membrane mediates the activation kinases PKC and PKD. PKC substrates regulate different aspects of the T cell activation process, such as cell adhesion, establishment of polarity and transcription. MTOC, microtubule organizing center; MyoRLC, myosin regulatory light chain; NMII, nonmuscle myosin.