STEAP4 and obesity due to melanocortin 4 receptor deficiency: To verify the core mechanism by which the downregulation of STEAP4 expression in adipocytes promotes obesity, we interfered with STEAP4 expression in 3T3-L1 adipocytes through siRNA, and confirmed that its downregulation can directly lead to mitochondrial dysfunction, manifested as increased mitochondrial ROS production and decreased ATP production.