PRDM9 and posterior cortical atrophy: Meanwhile, metformin significantly reduced the mRNA level of SUV39H1, a histone methyltransferase of histone 3 lysine 9 (H3K9) by 69% in C4-2B (Figure 1e) and 47% in PC-3 (Figure 1f) PCa cells determined by semiquantitative PCR assays.