STEAP4 and Tangier disease: We previously showed that hepatic STAMP2 plays a pivotal role in alleviating either high-fat-diet (HFD)- or environmental-pollutant (polychlorinated biphenyl, PCB)-induced NAFLD and upregulation of STAMP2 using adenoviral STAMP2 ameliorates hepatic steatosis, inflammation, and iron overload in NAFLD, in in vivo and in vitro models [24,25,26,27,28].