Treatment with PGE₂ or the EP4 agonist enhances hematopoietic recovery from myelosuppression in vivo. (A) Representative FACS profiles of LSK cells in control- and PGE₂-treated mice 2, 4, 6, and 8 days after 5-FU injection. Twice-daily injections with PGE₂ (6 mg/kg body weight, IP) or ethanol were commenced the day after 5-FU injection. (B) The percentage of LSK cells in the Lin^– fraction in control and PGE₂-treated mice 2, 4, 6, and 8 days after 5-FU injection. Data represent means ± SD (*P < .01; **P < .05, n = 5/group). Representative data from 2 independent experiments are shown. (C) Number of LSK cells in control and PGE₂-treated mice 2, 4, 6, and 8 days after 5-FU injection. Data represent means ± SD (**P < .05, n = 5/group). (D) Representative FACS profiles of LSK cells in control mice and EP4 agonist–treated mice 8 days after 5-FU injection. Twice-daily injections with the EP4 agonist (50 μg/kg body weight, IP) or ethanol were commenced the day after 5-FU injection. Representative data from 3 independent experiments are shown. (E) The percentage of LSK cells in the Lin^– fraction in control mice and in PGE₂- and EP4 agonist–treated mice 8 days after 5-FU injection (*P < .01; **P < .05, Control: n = 18, PGE₂: n = 13, EP4 agonist: n = 14). (F) Number of LSK cells in control mice and in PGE₂- and EP4 agonist–treated mice 8 days after 5-FU injection. The data indicates the number of LSK cells per mice (2 femurs and 2 tibias) (*P < .01, Control: n = 18, PGE₂: n = 13, EP4 agonist: n = 14).