CXCL12α protein expression in the bone marrow following G-CSF treatment. (A) G-CSFR mutant mice (n = 7, each) were treated with G-CSF (100μg/kg/d) for 5 days and the amount of CXCL12α protein in the bone marrow extracellular fluid measured by ELISA. Data represent the mean ± SD. *P < .05 compared with untreated mice of the same genotype. (B) Plot of CXCL12α protein in the bone marrow versus the log of number of CFU-Cs in the blood on day 5 of G-CSF treatment (P < .001).