PECAM1 and neoplasm: Total CECs consist of endothelial progenitor cells (EPCs) mobilized from the bone marrow by tumor angiogenesis factors and the mature CECs derived and differentiated from EPC4, 5 or shed from the wall of the micrangium.6 Early EPCs express CD34+/CD133+/VEGFR‐2+, and late EPCs express CD133−/VEGFR‐2+/CD105+/CD62E+/CD31+/CD146+/CD144+/VWF+.