SDF-1, in contrast to TPO, does not phosphorylate MAPK, AKT, and STAT proteins in human platelets.

Western blot analysis of MAPK p42/44 phosphorylation (A), AKT phosphorylation (B), STAT-3 (Tyr 705) (C), and STAT-5 (D) phosphorylation in normal human peripheral blood platelets. Platelets were nonstimulated (lane 1) or stimulated for 10 minutes by 100 ng/mL TPO (lane 2) or for 1 minute by 500 ng/mL SDF-1 (lane 3). Equal loading in the lanes was evaluated by stripping the blot and reprobing with anti-MAPK p42/44, AKT, and STAT-5 antibodies. The experiment was repeated 3 times with similar results.