Expression of mdr 1 was nagative in ATRA resistant HL60 cells. It was negative in resistant APL cells even after ATRA treatment.

• 结果 对全反式维甲酸 (ATRA)耐药的HL6 0细胞MDR1阴性 ,初发时MDR1为阴性的APL患者复发后仍为阴性。