PROM1 and cancer: Using transcriptional initiation events from a representative panel of 72 developmental, cancer, and normal CAGE (De Hoon and Hayashizaki, 2008; Hoskins et al., 2010; Kurosawa et al., 2010) libraries we have characterized PROM1 promoter utilization, confirming the activity of four out of five known promoters (P1–P4) and one novel alternate promoter (P6).