PPARG and obesity due to melanocortin 4 receptor deficiency: Pparg promoter methylation correlates with low expression of PPARγ in preadipocytes of the mouse cell line 3T3-L1 [152], and preadipocyte differentiation to mature adipocytes is accompanied by progressive Pparg promoter demethylation as the expression of PPARγ protein increases, whereas obesity is associated with the reverse effect, with Pparg methylation increasing as PPARγ expression decreases [152].