BMI1 and cancer: Consistent with recent studies demonstrating overexpression of PcG genes in cancer (Vonlanthen et al, 2001; Sellers and Loda, 2002; Kleer et al, 2003; Raaphorst et al, 2003; Breuer et al, 2004; Kim et al, 2004; Shi et al, 2005), we found that both BMI-1 and EZH2 are strongly expressed by a variety of tumours (Table 3; Supplementary Material; Figure 1).