PECAM1 and neoplasm: Both overall CD31 staining and microvessel density (MVD) were significantly higher in MDA-MB-231 tumours (Fig. 3b, c; CD31: 0.04 ± 0.006 MCF-7 vs. 0.21 ± 0.03 MDA-MB-231; MVD: 5.3 × 10−5 ± 0.4 × 10−5 MCF-7 vs. 1.1 × 10−4 ± 0.7 × 10−5 MDA-MB-231).