Platelets selectively take up VEGF, without a corresponding increase of the protein in plasma. VEGF protein was labeled with radioactive iodine, and approximately 50 ng of ¹²⁵I-labeled VEGF in 100 μL of Matrigel was implanted subcutaneously in the left flanks of C57/BL6 mice. Three days later, the mice were killed and 1 mL of citrated blood, as well as liver, kidney, spleen, and Matrigel pellet were collected. The radioactivity of each tissue sample was quantified on a gamma counter, the value corrected for differences in tissue weight, and expressed as counts per minute per gram of tissue. The experiment was repeated on 2 separate occasions with 5 mice per experiment, and the graph represents mean plus or minus SE of 1 of the experiments.