PTEN and prostate carcinoma: ChIP-qPCR analysis further confirmed that there was substantial enrichment of EZH2 binding at the FOXO1 promoter in both C4-2 (PTEN-negative) and 22Rv1 (PTEN-positive) prostate cancer cells (Figure 1C), indicating that EZH2 binds to the FOXO1 gene promoter in both cell lines.