Recent studies have revealed that the PCGF family of proteins (PCGF1 (Nspc1), PCGF2 (Mel-18), PCGF3, PCGF4 (Bmi1), PCGF5 and PCGF6 is robustly elevated in diverse human cancers and promotes cancer progression [21, 32, 33]. This evidence concerns the gene BMI1 and cancer.