It is reported that the biogenesis of let-7 family members, which seem to act as tumour suppressor miRNAs, is negatively regulated posttranscriptionally by Lin28 in embryonic stem cells and certain cancer cell lines (Heo et al, 2008; Newman et al, 2008; Piskounova et al, 2008; Viswanathan et al, 2008; Hagan et al, 2009). The gene discussed is LIN28A; the disease is cancer.