PAK4 and cancer: Many preclinical and clinical studies have reported that overexpression or genomic amplification of PAK1, PAK2, and PAK4 is often detected in multiple tumor tissues, including pancreatic, ovarian, breast, and gastric cancers (King et al., 2014; Ong et al., 2015; Wang et al., 2015; Prudnikova and Chernoff, 2017; Wang et al., 2020), warranting these three isoforms as potential targets for cancer treatment.