IPA assay showed that interleukin-6 (IL-6), interleukin-15 (IL-15), FGF21 (described in 1.1), and brain-derived neurotrophic factor (BDNF) are involved in the development of NAFLD through NF-κB (Figure 4). Here, FGF21 is linked to metabolic dysfunction-associated steatotic liver disease.