These downregulated AQP7 levels may promote adipocyte enlargement and reduced basal lipolysis, which then possibly further leads to reduced cholesterol levels in plasma membrane caveolae [90], since reductions in cholesterol in the plasma membrane can induce the internalization of caveolins (the main structural protein of caveolae) [106], and this internalization subsequently impairs insulin signaling [107], which may be one of the reasons why obesity leads to T2DM. Here, INS is linked to obesity due to melanocortin 4 receptor deficiency.