We observed a decreased protein expression of UPR-induced transcription factors ATF4 and CHOP when adding imatinib to oligomycin or thapsigargin and hypothesize that this combination of ER stress induction and UPR inhibition of CML cells made them more sensitive to cell death. The gene discussed is ATF4; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.