FSTL1 and metabolic dysfunction-associated steatohepatitis: Meanwhile, we found that the protein expression of FSTL1 did not change in the GAS F4MKO mice fed a normal chow diet, whereas it decreased significantly in the GAS, soleus, and quadriceps of F4MKO mice under NASH model conditions (Fig. 3a, Supplementary Fig. 4a–c); the same was observed with plasma FSTL1 (Fig. 3c).