APOA1 and obesity due to melanocortin 4 receptor deficiency: Several recent studies aimed to answer this question studied the role of apoA-I in regulating obesity through two main lines of investigation: (1)overexpression of genes that encode apoA-I in mouse models; (2) administration of apoA-I mimetics D-4F and L-4F, which share structural and biological features of native apolipoprotein A-I, to mimic increased plasma apoA-I level in mouse models.