PAK1

PAK1 is a p21-activated serine/threonine kinase that links Rac/Cdc42 signaling to cell motility, survival, proliferation, cytoskeletal organization, transcription, and translation^[1]. Mechanistically, PAK family kinases act as downstream effectors of Rho GTPases, with vertebrate PAKs supporting cytoskeletal remodeling, focal adhesion assembly, cell migration, and synaptic plasticity^[2]. In cancer models, PAK1 functions as a signaling node downstream of HGF/MET in pancreatic adenocarcinoma, where PAK1 inhibition blocks cytoskeletal effector signaling, tumor cell motility, tumor growth, and metastasis^[3]. In colorectal cancer, Group I Pak inhibition impedes adenoma-to-carcinoma transition by reducing β-catenin activity and suppressing an epithelial-mesenchymal transition program^[4]. In neurological disease models, PAK1 knockdown reduces ATXN1 levels in mammalian cells, and pharmacological PAK inhibition decreases ATXN1 levels in an SCA1 mouse model^[5]. Compared with related isoforms, PAK1 belongs to Group I PAKs, and inhibitor development must address whether to target one isoform or multiple PAK isoforms^[1][5]. For experimental applications, ATP-competitive inhibitors, allosteric inhibitors, and peptide inhibitors provide laboratory tools for studying PAK1 biology and disease contexts^[6].