Here we show that PI3K-C2β regulates mitogen-activated protein kinase kinase (MEK1/2) and extracellular signal-regulated kinase (ERK1/2) activation induced by foetal bovine serum (FBS) or epidermal growth factor (EGF) in prostate cancer (PCa) cell lines. The gene discussed is MAPK3; the disease is Familial prostate cancer.