In GIST cell lines with aberrant KIT activation and imatinib resistance, HSP90 is necessary for proper KIT folding, and HSP90 inhibitor TAS-116 reduces autophosphorylation-activated KIT and inhibits tumor growth.191 HSP90 inhibition combined with lapatinib has also been effective in breast cancer.192. The gene discussed is HSP90AA1; the disease is gastrointestinal stromal tumor.