PGP and chronic myelogenous leukemia, BCR-ABL1 positive: Antisense oligonucleotides were shown to reduce the amount of MDR1/mRNA, and P-gp expression in human chronic myelogenous leukemia cells (K562) expressing P-gp[220] and were also shown to increase doxorubicin accumulation in human glioblastoma and endothelial cell lines expressing P-gp[221].