Effect of GM-CSF on expression levels of SOCS-1, -2, and -3 as detected by Western immunoblotting. OCIM2 cells were incubated with GM-CSF at a concentration of 0.05 μg/mL in a time-dependent fashion ranging from 20 minutes to 6 hours. Upon stimulation with GM-CSF, levels of proteins of SOCS-2 and -3 increased, with a maximum response at 40 minutes to 1 hour. Thereafter, protein levels either remained stable (SOCS-2) or declined (SOCS-3). Representative data from 3 different experiments are shown.