In further analysis, 2 out of 4 patients with p-gp negative cancers (according to IHC staining) had CR (50%) while 5 out of the 12 patients with p-gp positive cancers had CR (41.6%), further suggesting that zosuquidar might not provide anticipated efficacy when added to standard induction chemotherapy to AML (acute myeloid leukemia). This evidence concerns the gene PGP and cancer.