Serine/threonine-protein kinase PAK 2 is an enzyme that in humans is encoded by the PAK2 gene. PAK2 is one of three members of Group I PAK family of serine/threonine kinases. The PAKs are evolutionary conserved. PAK2 and its cleaved fragment localize in both the cytoplasmic or nuclear compartments. PAK2 signaling modulates apoptosis, endothelial lumen formation, viral pathogenesis, and cancer including, breast, hepatocarcinoma, and gastric and cancer, at-large. Discovery The human PAK2 was identified as a downstream effector of Rac or Cdc42. Gene and spliced variants The PAK2 gene is about 92.7-kb long. The gene contains 15 exons and generates three alternatively spliced transcripts - two of which code proteins of 524 amino acids and 221 amino acids, while the third one is a 371-bp non-coding RNA transcript(Gene from review) There are two transcripts generated from the murine PAK2 gene, a 5.7-kb transcript coding a 524 amino acids long polypeptide and a 1.2-kb long non-coding RNA transcript. Protein domains Similar to PAK1, PAK2 contains a p21-binding domain (PBD) and an auto-inhibitory domain (AID) and exists in an inactive conformation. The p21 activated kinases (PAK) are critical effectors that link Rho GTPases to cytoskeleton reorganization and nuclear signaling. The PAK proteins are a family of serine/threonine kinases that serve as targets for the small GTP binding proteins, CDC42 and RAC1, and have been implicated in a wide range of biological activities. The protein encoded by this gene is activated by proteolytic cleavage during caspase-mediated apoptosis, and may play a role in regulating the apoptotic events in the dying cell. Function The p21 activated kinases (PAK) are critical effectors that link Rho GTPases to cytoskeleton reorganization and nuclear signaling. The PAK proteins are a family of serine/threonine kinases that serve as targets for the small GTP binding proteins, CDC42 and RAC1, and have been implicated in a wide range of biological activities. The protein encoded by this gene is activated by proteolytic cleavage during caspase-mediated apoptosis, and may play a role in regulating the apoptotic events in the dying cell. Upstream activators PAK2 kinase activity is stimulated by transforming growth factor β in fibroblasts, by proteinase inhibitor alpha2-macroglobulin binding to GRP78 in prostate cancer cells, by its phosphorylation by AMP-activated protein kinase in stem and cancer cells and eryptosis. PAK2 is cleaved through activated caspase-3 in fibroblast and cancer cells exposed to ultraviolet, hyperosmotic shock, and ionizing radiation. Inhibitors The levels of PAK2