The tumor-associated change in platelet level of an angiogenesis regulator may be continuous. Platelet lysates from mice xenografted with human liposarcoma cells were longitudinally analyzed using SELDI-ToF at baseline, and up to 120 days after implantation of the tumor. The figure depicts an illustrative example of how the levels of an angiogenesis regulator (PDGF) are sustained in platelets for the duration of the experiment. Mice bearing dormant variant of human liposarcoma increase the platelet level of PDGF between 19 and 30 days after tumor implantation, and the level remains elevated for the duration of the experiment. The experiment was repeated on 2 separate occasions with 5 mice per experiment, and the graph represents mean plus or minus SEM.