PAK4 and cancer: The serine/threonine p21-activated kinases (PAKs) are key cell signaling hubs with proven roles in several of the hallmarks of cancer.5 Specifically, p21-activated kinase 4 (PAK4) can confer apoptosis resistance and anchorage-independent cell growth and regulate important aspects of cell proliferation, cell migration and drug-resistance.6 PAKs are frequently overexpressed in cancer, often correlated to poor patient outcome.6