BMI1 and colorectal cancer: During cellular senescence, the expression of BMI1 is often reduced, affecting cell cycle arrest and the production of the SASP.[47] Next, we knocked down BMI1 in the colorectal cancer cell lines RKO and HCT116, and upon knockdown, the cells exhibited features of senescence, including upregulated expression of p53 and p21, indicating that downregulation of BMI1 significantly promoted cellular senescence.