PECAM1 and neoplasm: Assessment of the co-localisation of Hoechst 33342 and CD31 (Figure 3A, Table 2) revealed that the percentage of the total vessels perfused at the time of Hoechst 33342 injection was 17.1% lower in MLN0518 than vehicle treated tumours (p<0.01), which equated to a 37.5% reduction in an overall perfused vessel area in treated versus control tumours (p<0.01).