Studies with aqp7−/−-null mice showed a three-fold reduction in glycerol release into the bloodstream [353,354], leading to adult-onset obesity and insulin resistance; the knockdown of AQP7 in mouse 3T3-L1 adipocytes resulted in two-fold lower glycerol secretion [354]. Here, AQP7 is linked to obesity due to melanocortin 4 receptor deficiency.