Kinetics of TGF-β₁–induced inhibition of Fas response. Two thousand Lin⁻ BM cells were plated in IMDM containing 20% FCS, 1.2% methylcellulose supplemented with 20 ng/mL GM-CSF, and 20 ng/mL TNF-α in the absence (▤) or presence (▪) of 0.5 μg/mL Jo2. TGF-β₁ (20 ng/mL) was added as indicated at initiation of culture (0 hour) or after 24, 48, or 96 hours of incubation. Colonies were scored after a total of 7 to 9 days of incubation at 37°C and 5% CO₂ in air. An irrelevant hamster IgG had no effect on colony formation. Results represent the mean values of three separate experiments with duplicate determinations; error bars show the SEM.