FAS and metabolic dysfunction-associated steatotic liver disease: The absorption of BAs into the liver can enhance the FXR-related signaling pathway, which not only induces the expression of the downstream target gene SHP, negatively regulates SREBP1c, and downregulates the expression of genes related to fatty acid syntheses, such as FAS and ACC, to reduce hepatic lipogenesis, but also reduces insulin resistance (IR) to ameliorate NAFLD (Figure 3–Pathway III).