Pak1, also known as p21-activated kinase 1, is a serine/threonine-protein kinase. It is an effector protein of the small G proteins Rac and Cdc42, and is involved in multiple signal transduction pathways. Pak1 regulates key cellular developmental processes such as cell motility, survival, proliferation, cytoskeleton organization, and extracellular matrix function, as well as transcription and translation [4].

In melanoma, Pak1 may decrease cell sensitivity to programmed cell death, stimulate growth-promoting molecular pathways, and contribute to an immunosuppressive tumor microenvironment. Inhibition of Pak1 enhances the potency of anti-melanoma regimens [1].

In glioblastoma, Pak1 is upregulated and promotes tumor development by enhancing hypoxia-induced autophagy through phosphorylating ATG5, and its silencing blocks autophagy and tumor growth [2].

In Down syndrome, the enhanced activity of the DSCAM/Pak1 pathway affects neurogenesis in iPSC-derived cerebral organoids, and suppressing this pathway reverses abnormal neurogenesis [3].

In conclusion, Pak1 is crucial in regulating various cellular processes. Research on Pak1 using gene-knockout or conditional-knockout models has revealed its roles in diseases like melanoma, glioblastoma, and Down syndrome. Understanding Pak1's functions provides insights into disease mechanisms and potential therapeutic strategies for these conditions.