Insulin-like growth factor 2 (IGF2) is often overexpressed in paediatric cancers, including Wilms' tumours and sarcomas. IGF2 is maternally imprinted, and increased expression is attributed in part to loss of imprinting at fetal promoters. To look for other modes of regulation of IGF2 expression, Liu et al. examined microRNA expression in primary Wilms' tumours and found that miR-483-5p, which is located in an intron of IGF2, was overexpressed compared with fetal kidney tissue (from which Wilms' tumours are thought to arise). miR-483-5p upregulated the transcription of IGF2 mRNA in Ewing's sarcoma cell lines (Wilms' tumour cell lines are scarce), and nuclear miR-483-5p bound the 5′ untranslated region of IGF2 mRNA and enhanced its transcription. Ectopic expression of miR-483-5p in sarcoma cells increased tumour size in mice, reinforcing the role of this microRNA and positive feedback regulation of its host gene in tumorigenesis.