PGP and leukemia: Mifepristone inhibits the activity of P-gp in a gastric cell line SGC7901/VCR (37) and in KG1a leukemia cells (23), enhances doxorubicin cellular accumulation in resistant human K562 leukemia cells (53), and increases the concentration of cisplatin in the tumors of mice given a combined cisplatin/mifepristone treatment (54).