Loss of Cxcl12 results in faster hematologic re-establishment under 5-FU challenge in mice deficient in Cxcl12. (A) The peripheral blood profile 7 days after a single 5-FU treatment (200 mg/kg body weight) revealed that leukopenia was less severe in Cxcl12-cKO mice. Peripheral blood was collected at day 0 and day 7 after 5-FU treatment. WBC, neutrophil, and lymphocyte counts for individual mice were compared with their day-0 value (mean ± SEM; *P < .05, **P < .01; n = 8). (B) BM regeneration was demonstrated by BM cellularity recovery after 5-FU treatment. Bar graph shows the BM nucleated cells from one femur in each specific time point (mean ± SEM; *P < .05; each time point n = 3). (C) BM LSK cell population analysis in Cxcl12-WT and Cxcl12-cKO mice 7 days after 5-FU challenge (mean ± SEM; *P < .05; n = 4 each). (D) Kaplan-Meier survival curve (log rank test P = .0484; n = 10 each) for mice treated by a single lethal dose of 5-FU (500 mg/kg body weight).