To determine whether carfilzomib, ixazomib and delanzomib have an effect on GIST cell viability and/or apoptosis, imatinib (IM)-sensitive (GIST882, KIT p.K642E; GIST-T1, KIT p.V560_Y578del) and IM-resistant (GIST48, primary KIT p.V560D/secondary KIT p.D820A; GIST430, primary KIT p. V560_L576del/secondary KIT p.V654A) GIST cell lines were treated with increasing concentrations covering a 100,000-fold concentration range (0.1 nM–10.0 μM). The gene discussed is KIT; the disease is gastrointestinal stromal tumor.