Endothelial cell migration increases in the presence of Tsp-1^−/− platelet lysates. (A) Endothelial migration was measured in the absence of VEGF (Ctrl.) or in response to VEGF (5 ng/mL) in the presence of thrombin, rTSP-1, or platelet lysates from wild-type or Tsp-1^−/− platelets activated by thrombin (P = .03). (B) Endothelial cell migration was measured in the absence of VEGF (Ctrl.) or in response to VEGF (5 ng/mL) in the presence of thrombin, or thrombin-treated platelet lysates from wild-type mice or tumor-bearing (500 mm³) wild-type mice (P = .001).