In contrast, GIST 430 cells exhibiting primary KIT exon 11 deletion (V560_L576del) and secondary KIT exon 13 mutation (V654A) maintain survival and IM resistance mainly via KIT-dependent mechanisms, thereby explaining the lack of synergy between FGFR and VEGFR inhibitors for this particular IM-resistant GIST cell line. Here, KDR is linked to gastrointestinal stromal tumor.