While short-term exposure to high concentrations of PEITC (6–12 μM for 48 h) was sufficient to reduce tumor cell expression of BMI-1 (Fig. 6b), marked decreases in the expression of key PcG complex proteins SUZ12 and EZH2 were only observed after long-term treatment (2.5 μM PEITC for 6 weeks). This evidence concerns the gene EZH2 and neoplasm.