BMI1 and malignant colon neoplasm: Furthermore, these cells cannot form tumors when injected into nude mice.27, 28, 29 Bmi1 has been previously reported to be a crucial regulator of stem cell self-renewal and is upregulated in various types of cancers, including breast, pancreas and colon cancers as well as HCC.6, 13, 14, 23 However, the role of Bmi1 on HPCs has not yet been well documented.