KDR and obesity due to melanocortin 4 receptor deficiency: Evidence suggests that obesity is accompanied by endothelial cell dysfunction and decreased vascular density44 and that modulation of endothelial cell function through some of the key molecules, including transcription factors (PGC-1α, PPARγ, and NF-κB), angiogenic signaling (VEGF/vascular endothelial growth factor receptor 2 (VEGFR2) and angiopoietin 2 (ANGPT2)/TEK tyrosine kinase (TIE2)), insulin signaling (insulin receptor), and mediators of fatty acid transporters (CD36 and PPARγ), is sufficient to regulate the progression of obesity45.