SDF-1 does not modify EPC cell cycle. (A-B) FACS analysis of PI-stained one-day–cultured c-kit⁺ cells ± 100 ng/mL SDF-1. The addition of the chemokine did not result in suppression of apoptosis or in progression into cell cycle as evidenced by the percentage of cells in sub-G1 (brackets in A) and G1 phase, respectively. (B) Average of 3 independent experiments ± SE; filled bars indicate control treatment; open bars, 100 ng/mL SDF-1. (C-E) SDF-1 does not modify the percentage of differentiated EPCs in S-phase after 7 days of culture. BrdU incorporation assays in differentiated EPCs were performed, and BrdU⁺ cells (arrows in C-D) were counted in randomly selected microscope fields among Hoechst 33258⁺ cells. (E) Average of 3 independent experiments ± SE. C indicates control-untreated cells.