Metformin regulated expression of 19 genes associated with prostate cancer, such as AR, Nxk3.1, KLK3 (PSA), CDKN1A (p21), CDKN1B (p27), and CCND1 (cyclin D1) (Table 1 and data not shown). The gene discussed is CDKN1B; the disease is prostate carcinoma.