In embryonic stem cells and cancer cells, TUT4 and TUT7 (TUT4/7) have been shown to oligo-uridylate precursors of let-7 family miRNAs in concert with the processivity factor Lin28 (Heo et al, 2008, 2009; Hagan et al, 2009; Yeom et al, 2011; Thornton et al, 2012). This evidence concerns the gene TUT7 and cancer.