BMI1 and neoplasm: Since PEITC treatment up-regulated the expression of pro-apoptotic genes in SW620 cells and BMI-1 overexpression was able to rescue the viability of tumor cells undergoing PEITC treatment (Fig. 7a,b), we next investigated whether enhanced expression of BMI-1 could protect HCT116 cells against PEITC-mediated apoptosis.