To determine the functional significance of our findings that ARID4B is a transcriptional activator of the PI3K subunits PIK3CA and PIK3R2 (Table 1 and Fig. 1a, b), we investigated the role of ARID4B in the development of prostate cancer harboring PTEN deficiency. The gene discussed is PIK3CG; the disease is Familial prostate cancer.