-Partial demethylation of the CpG island in the promoter of GSTP1 in all cell lines-Demethylated the CpG island of the promoter of EPHB2 in the PC-3 line-Demethylated the CpG islands of the promoter of RASSF1A in the LNCaP line-Increased the nuclear expression of GSTP1 in line DU-145-Increased the expression of EPHB2 in the nucleus of line PC-3 and the cytoplasm of DU-145 cells⇒ Epigenetic modifications of DNA,such as the promoter CpG island demethylation of tumor suppressor genes, might be related to the protective effect of genistein on prostate cancer. This evidence concerns the gene GSTP1 and prostate carcinoma.