CD9 and cancer: Interestingly, it has been shown that CD9 localized along lateral junctions of endothelial (CD34 positive) and epithelial cells [25]; more specifically, Longo et al., similarly to our findings, described that endothelial cells had an active redistribution of CD9 to the points of melanoma cell insertion, and CD9 expression was mostly concentrated at tumor cells-endothelial cells contact areas, suggesting a stated role of CD9 in the extravasation phase of cancer cell invasion.