Although other tumor suppressors may also be repressed by the PRC1 complex in the process of tumorigenesis [13, 14], the oncogenic function of BMI1 and other PRC1 components has been mainly attributed to their repression of the cyclin-dependent kinase inhibitor 2A (CDKN2A) locus [15]. The gene discussed is CDKN2A; the disease is neoplasm.