Incorporation of BGJ398 into an IM-based treatment schedule induced a substantial decrease of the numbers of mitotic and FGF-2-positive cells in GIST T-1R xenografts (Figure 6C,D, respectively), which correlated with the decrease of tumor size and volume in IM-resistant xenografts, thereby revealing that the activation of FGF-signaling is important for acquired resistance to IM in vivo. Here, FGF2 is linked to gastrointestinal stromal tumor.