When we conducted histologic analysis to compare the progression of NASH between Gdf15−/− and wild-type mice fed AMLN diet, we observed aggravated fibrosis (Fig. 4f,g and Supplementary Fig. 4d), increased infiltration of F4/80-positive cells (Fig. 4h and Supplementary Fig. 4e,f), increased expression of inflammatory cytokines (Fig. 4h) and increased serum ALT/AST levels (Fig. 4i) in Gdf15−/− mice compared to control mice fed AMLN diet for 30 weeks. Here, GPT is linked to metabolic dysfunction-associated steatohepatitis.