CD31+/VEGFR-2+ cells are crucial in the neovascularisation process and have recently been shown to be elevated in breast cancer patients to significantly correlate with tumour size and to rapidly decline after removal of the tumour, suggesting a possible induction by tumour-driven angiogenic stimuli (Richter-Ehrenstein et al, 2007). This evidence concerns the gene PECAM1 and breast carcinoma.