HCC was visible in both macroscopic and histological examinations of all Fah−/− mice (n = 12), and metformin treatment significantly delayed tumour formation: only 50% of the metformin‐treated Fah−/− mice developed HCC after 12 weeks of 2.5% NTBC treatment (n = 12) (Figure 2C). The gene discussed is FAH; the disease is neoplasm.