PAK4

P21 activated kinase 4 (PAK4) is a recently discovered serine/threonine protein kinase and is a member of the PAK family. The PAK family has six members and is classified into Class I and Class II according to amino acid sequence and function. Class I includes PAK1, PAK2, and PAK3, and Class 11 includes PAK4, PAK5, and PAK6. Class II PAKs contain the pBD and kinase domains at the N-terminus and the c-terminus, respectively, and contain the CRIB region in the pBD, but do not contain the self-inhibitory domain. PAK4 in class II differs greatly in sequence from other PAKs. The GBD and kinase domains of PAK4 have less than 50% homology with PAK1. The GBD and kinase regions of PAK4 have seven putative SH3 binding sites, one RhoA GEF binding site and one integrin binding domain. Human p21 activated kinase 4 (PAK4) gene is located on chromosome 19q13 and is 3 064 bp in length, encoding a total of 591 amino acids with a relative molecular mass of 72,000. P21-activated kinase 4 (PAK4) plays an important role in a range of cellular functions, such as cell cycle, cell proliferation, apoptosis, and cytoskeletal reorganization. In recent years, it has been found that PAK4 is overexpressed in many tumor cells and participates in tumorigenesis and migration infiltration through multiple signaling pathways.