NOX4 deletion accelerated hepatocyte proliferation after partial hepatectomy (Herranz-Itúrbide et al., 2021)—which is an essential component of the response—but also accelerated proliferation and migration in hepatocellular carcinoma (Crosas-Molist et al., 2014), suggesting that inhibiting NOX4 could exacerbate the progression of liver disease associated with obesity. The gene discussed is NOX4; the disease is obesity due to melanocortin 4 receptor deficiency.