In vivo BrdU incorporation in blood neutrophils of G-CSF–treated mice. Mice (n = 3 for each genotype) were injected daily with G-CSF. After 4 days, 150 μL of BrdU (10 μg/mL in PBS) was injected intraperitoneally and blood was collected and analyzed at various times. Smears were made for May-Grünwald Giemsa and BrdU staining. Error bars represent standard deviation. gcsfr-wt/wt, (▪); gcsfr-wt/▵715, (┌); gcsfr-▵715/▵715, (□).