PPARG and obesity due to melanocortin 4 receptor deficiency: We found that Twist 1 was negatively correlated with obesity development and that retroviral interference of Twist 1 expression did not impair the process of lipid formation in cultured 3T3-L1 preadipocytes; however, retroviral interference of Twist 1 altered the expression of PPARγ and influenced the secretion of multiple adipokines, mainly interleukins, growth factors, chemokines, and their receptors, thus providing a prospective mechanism linking Twist 1 expression with obesity or obesity-associated diseases.