MAPK1 and prostate cancer: KS6A2/RPS6KA2, also known as RSK/RSK3, is a member of the RSK serine/threonine-protein kinase family that acts as a downstream effector of ERK in the MAPK1/ERK2 and MAPK3/ERK1 signaling pathway, mediating cellular proliferation and survival in prostate cancer [75].