PECAM1 and neoplasm: Immunofluorescence staining for the endothelial cell marker CD31 (cluster of differentiation 31) in tumor tissues extracted from mice treated with 1 showed decreased blood vessel density compared with those obtained from mice treated with curcumin or vehicle (Fig. 7E), suggesting that 1 suppressed tumor growth in a U87MG mouse xenograft model by inhibiting angiogenesis (Fig. 7A).