In addition, RT-PCR indicated that the mRNA levels of Col1a2 and α-Sma on an HFD were approximately the same in both substrains (Fig. 7D and Supplementary Fig. 6), confirming no marked difference in the progression of the hepatic fibrosis between the BL6J and BL6N mice in the HFD-induced NASH model. Here, COL1A2 is linked to metabolic dysfunction-associated steatohepatitis.