COL3A1 and steatosis: MUP-uPA mice suffer from constitutively elevated endoplasmic reticulum (ER) stress in the liver and are a widely used model of steatosis-driven liver fibrosis and HCC development.23,24 Feeding MUPLAPNTG mice HFD+DOX for 20 weeks, we observed a significant reduction in the liver expression of fibrotic genes including SMA, Col3a1, and Col4a4 (Figures 2O–2Q).