HDAC9 and gastrointestinal stromal tumor: The inhibition of autophagy by chloroquine increased cell death in imatinib-resistant, BCR­ABL­positive CML cell lines and enhanced the effect of the HDAC inhibitor vorinostat [29-31].Chloroquine and the antimalarial drug quinacrine sensitized gastrointestinal stromal tumor cells toward treatment with imatinib both in vitro and in vivo [32].