FABP4 and obesity due to melanocortin 4 receptor deficiency: aP2-nSREBP1c mice are on an FVB background (45), which have about 60 genetic variants that directly affect protein structure or mRNA stability, and provide resistance to diet-induced obesity, whereas LmnaADKO mice are on a C57BL/6J background, which also has genetic variants that affect protein function but that increase susceptibility to diet-induced obesity (46, 47).