While the normal-chow diet-fed Tsc1−/− animals displayed evidence of hepatic and systemic insulin resistance, their livers did not show signs of steatosis, and the corresponding levels of hepatic triglyceride and expression of lipogenic genes (e.g., SREBP1, ACLY, FASN) were similar to those of the wild-type littermates. The gene discussed is TSC1; the disease is steatosis.