KIT and gastrointestinal stromal tumor: Taken together, our IHC data demonstrates a substantial increase of FGF-2 nuclear expression in GIST after the initiation of IM-based therapy (e.g., FGF-2 nuclear staining was observed in 6/12 cases (50%) of IM-naive GISTs and 6/7 cases (85.7%) of IM-treated GISTs (as shown in Figure 7B), thereby revealing the activation of FGF-signaling as a compensatory mechanism of IM resistance in KIT-inhibited GISTs in vivo.