KIT and gastrointestinal stromal tumor: In order to exploit the GIST lines' dependence on constitutive KIT expression irrespective of KIT mutation status, we performed MTT viability assays and 11-point dose response curves with imatinib (positive control) or ATO using both imatinib-sensitive (GIST-T1 and GIST882) and imatinib-resistant (GIST48IM) cells (n = 3/cell line/drug/concentration).