DICER1 and neoplasm: Inactivation of Dicer is associated with impaired maturation of miRNA (Cummins et al, 2006; Kumar et al, 2007; Wiesen and Tomasi, 2009) We have studied the expression of three mature miRNAs, namely miR-182, miR-221, and miR-21 that were involved in the tumourigenesis in Dicer knocked-down human tumour cells (Supplementary Figures S2A and B).