In conclusion, the present study demonstrated that the ABCB1 1236CT/3435CT/2677GT and 1236TT/3435TT/2677TT haplotypes are associated with lower P-gp activity and MMR in chronic-phase CML patients treated with a standard dose of IM (400 mg/day). The gene discussed is PGP; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.