Expression of HGF receptors in C/EBPα^-/- FL cells and morphology of C/EBPα^-/- FL cells grown in IL-3 and GM-CSF. RNA was extracted from E16 to 17 C/EBPα^+/+, C/EBPα^+/-, and C/EBPα^-/- FL and analyzed by Northern blot for the expression of M-CSFR and GADPH (A) or by RPA for GM-CSFRα, IL-6R, and gp130 according to the procedures outlined in “Materials and methods” (C). RPA signals were quantitated, relative to controls, by scanning densitometry (B). FL cells were harvested from E16 to 17 C/EBPα^+/+ and C/EBPα^-/- mice seeded into liquid cultures at 2 × 10⁵ cells/mL in cIMDM. Cells were removed from the cultures after 7 days of incubation (37°C) in the presence of IL-3 or GM-CSF, cytocentrifuged, and stained with Giemsa. Bright field photomicrographs were taken with a Leica DMLB microscope at a magnification of × 400 (D).