CXCR4 and obesity due to melanocortin 4 receptor deficiency: One important finding in the current study is that, although the circulating numbers of EPCs (C-kit/CD31+, Sca-1/KDR+, CXCR4/CD34+) showed no significant difference among the control, obese, and obesity control animals before CLI induction (Table 1), they were remarkably reduced in obese mice at the acute stage (i.e. 18 h after the CLI procedure) compared with that in the obesity controls.