Characteristics of mouse bone marrow–derived EPCs. (A) Phase-contrast images of freshly isolated EPCs in culture at various time intervals (20× objective lens). (B) Histograms of flow cytometric analysis of EPC markers on day 0, 3, 7, 10, and 14 of cell culture. (C) Immunofluorescent staining for endothelial cell markers on EPC in 2-week cultures. Green indicates VE-cadherin; red, E-selectin; blue, cell nuclei. (D) Western blotting analysis of the expression of flk-2, tie-2, E-selectin, and VE-cadherin in various time-cultured EPCs.