PECAM1 and neoplasm: Since pericyte coverage improves vessel maturation [27], we double stained for the endothelial cell marker CD31 and the pericyte marker α-smooth muscle actin (α-SMA), and observed the decreased microvessel density and the increased pericyte coverage of tumor vessels in the ISL (10 and 20 mg/kg)-treated groups when compared with the control (Fig. 4f-h).