PIN1 and metabolic dysfunction-associated steatohepatitis: Pin1 knockout (KO) mice are resistant to methionine choline-deficient (MCD) diet-induced NASH and fibrosis accumulation partially via the downregulation of peroxisome proliferator-activated receptor alpha (PPARα), as well as inhibition of NF-κB activation and its downstream inflammatory cytokines (Nozaki et al., 2009; Nakatsu et al., 2012).