RBP4 and acute coronary syndrome: Considering the similar circulating RBP4 level of patients with stable CAD in the two studies [35.8 ± 11.7 μg/ml vs. 34.74 (range 27.65–40.19) μg/ml], we speculated that different study populations are the main source of distinct findings in the view of the fact that patients with acute coronary syndrome are more likely to have a higher level of RBP4 than those with stable CAD (9).