For example, when VEGF/VEGFR is inhibited, angiogenesis can be maintained by secreting alternative factors, such as platelet-derived growth factor (PDGF) [24], basic fibroblast growth factor (bFGF) [25], and Ang2 [26], or by recruiting pro-angiogenic cells, such as trypsin-secreting mast cells, and promoting tumor growth [27]. This evidence concerns the gene KDR and neoplasm.