LEP and obesity due to melanocortin 4 receptor deficiency: Consistent with these findings, we previously reported that exogenous leptin administration, at concentrations mimicking obesity, increases PCNA (proliferation marker), vimentin (SM synthetic marker), and pCREB (pro-mitogenic regulator of VSMC proliferation) expression, accompanied by reduced SM-MHC (SM contractile marker) expression in ApoE−/− aortic vessels [21].