Dose-response curves of colony formation in the presence of cytokines in vitro. Colony formation was performed exactly as described in the legend to Fig 1. Data shown represent mean ± SEM of 1 of 4 independent experiments with 3 mice per group in each experiment. (A) Bone marrow cells from 6-week-old ICSBP^−/− (-○-) or ICSBP^+/+ (-▪-) mice were plated in the presence of rmIL-3, rmGM-CSF, or rmG-CSF at the indicated concentrations. (B) As in (A), with the addition of 10 ng/mL of rmSCF to the medium.