PECAM1 and cancer: Since Immunohistochemistry (IHC) is used in cancer subtyping for both intracellular and extracellular epitopes, we specifically chose 9 markers with a broad range of cellular localization, which occur intracellularly (cytokeratin and vimentin) and extracellularly (EpCAM, CD45, CD31, CD34, PD-L1, CXCR4 and CD14), Fig. 2 and Supplementary Figure 3.