Additional factors, including the Drosha-DGCR8 complex, hnRNPA1 (20,21), KSRP (21–23) and the Dis3L2 3′-5′ exonuclease (34,35) are present in vivo to assist Lin28 in modulating the production of mature let-7 as needed for development, cell differentiation and tumour suppression (5–13). The gene discussed is HNRNPA1; the disease is neoplasm.