FL cells were harvested from E16 to 17 C/EBPα^+/+ and C/EBPα^−/− mice and then seeded into liquid cultures at 2 × 10⁵ cells/mL in clMDM. Cells were removed from liquid cultures containing IL-3 or GM-CSF after 7 days and replated into soft agar colony assays at 5 × 10⁴ cells/mL in IL-3 and GM-CSF, respectively, according to the procedures described in “Materials and methods.” Secondary colony formation was evaluated after an additional 7 days, and results are presented as the mean number of colonies ± the standard error. These data are representative of 2 separate experiments.