Time course of STAT1 and STAT3 phosphorylation in IL-10–treated PMN and PBMC. Cells were treated with 100 U/mL IL-10, 100 U/mL IFNγ, and 1,000 U/mL G-CSF (A) or 20 ng/mL IL-10 (Peprotech), 100 U/mL IFNγ, and 100 ng/mL PMA (B) before lysis under denaturating conditions as described in Materials and Methods. One hundred fifty micrograms of PMN lysate and 80 μg of PBMC lysate were loaded on the gels; and immunoblots were performed using antibodies specific for tyrosine or serine phosphorylated forms of STAT1 and STAT3. Subsequent reblotting with the indicated anti-STAT1 or anti-STAT3 antibodies was performed to ensure that similar amounts of material were deposited in each lane. The data for each panel are representative of 4 independent experiments.