The inhibition of obesity-induced tumour growth and angiogenesis by metformin precisely phenocopied the blockade of IL-1 signalling, suggesting that metformin may act within this pathway, possibly by blocking IL-1β-mediated upregulation of Vegfa in adipocytes (Fig. 6f). The gene discussed is VEGFA; the disease is obesity due to melanocortin 4 receptor deficiency.