P38delta, Active

Mitogen-activated protein kinase (MAPK) cascades represent one of the major signal systems used by eukaryotic cells to transduce extracellular signals into cellular responses, and involved in a wide variety of cellular processes such as proliferation, differentiation, transcription regulation and development. The stress-activated protein kinase 4 (SAPK4), or p38 delta, is a member of the MAPK family that are activated by chemical and environmental stresses as well as by proinflammatory cytokines. SAPK4 has a TGY dual phosphorylation motif and is activated in response to cellular stresses and proinflammatory cytokines (1). MAP kinase kinases 3, and 6 can phosphorylate and activate this kinase. Transcription factor ATF2, and microtubule dynamics regulator stathmin have been shown to be the substrates of this kinase (2).