Although mast cells are considered to be bystanders in tumor immunology, additional pro-angiogenic effects of these cells are likely as they secrete relevant amounts of different VEGFs, FGF-2, trypase, and granzyme B. The latter has a pro-angiogenic effect via the enzymatic mobilization of ECM-bound FGF-1 (287, 288). Here, FGF2 is linked to neoplasm.