Effects of the EP4 agonist on HSPC regulation. (A and B) Effects of dmPGE₂ and the EP4 agonist on colony formation of LSK cells (300 cells/dish). Numbers of CFU-Cs (A) and HPP-CFCs (B) are shown. Data represent means ± SD (*P < .01; **P < .05, n = 3). Representative data from 3 independent experiments are shown. (C-E) Effect of dmPGE₂ and EP4 agonist treatment on HSPC engraftment. LSK cells (1 × 10³ cells/mouse) were treated with 10 μM of dmPGE₂, 10 μM, or 100 μM of the EP4 agonist or control were transplanted into lethally irradiated recipient mice. After 4 months of BMT, the frequencies of donor-derived cells in recipient mice were analyzed. Percentages of donor-derived cells engrafted in the PB (C), BM (E), and among BM LSK cells (F). Data represent means ± SD (*P < .01; **P < .05, control: n = 16, dmPGE₂: n = 11, 10 μM of EP4 agonist: n = 9, 100 μM of EP4 agonist: n = 9).