In vivo responses induced by G-CSF in (A) β_c -null mice and littermate controls and (B) GM-CSF transgenic mice and littermate controls. Progenitor cell cultures were stimulated with IL-3 and SCF in (A) and SCM in (B). Mean results at baseline and after G-CSF at 200 μg/kg/d for 5 days; four mice per group in (A) and three mice per group in (B). Error bars represent SD.