In 2009, Sun et al. [242] found that mice inhaling PM2.5 for more than 30 min showed an abnormal liver insulin signal, with an altered expression of endothelial NOS and protein kinase C. More recently, Yin et al. [247] demonstrated that PM2.5 exposure could inhibit the expression of PPARα and PPARγ, inducing hepatic steatosis, inflammation, and IR. The gene discussed is PPARA; the disease is fatty liver disease.