Synergistic activation of ERK1/2 by SDF-1α in combination with nonproliferative concentrations of other cytokines.

MO7e cells were stimulated for 15 minutes with SDF-1α alone, another cytokine alone, or SDF-1α plus another cytokine at the indicated concentrations. Cell lysates were analyzed by Western blotting using phosphospecific antibodies to ERK1/2 (Thr202/Tyr204). The membrane was reblotted with antibody recognizing p90RSK to show equal loading. (A) SDF-1α plus GM-CSF. (B) SDF-1α plus SLF. (C) SDF-1α plus TPO. (D) Columns represent relative band intensities of phospho-ERK ± SD from 3 experiments with similar results. *P < .05 (greater than additive).