As expected, the increased expression of phosphorylated forms of VEGFR1 and downstream signaling molecules, including AKT, MAPK, etc., was observed for FGF2-treated GIST T-1 cells (Figure 2A—right panel), thereby illustrating the activation of VEGF signaling in a FGF2-dependent manner. This evidence concerns the gene FLT1 and gastrointestinal stromal tumor.