ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: However, subsequent clinical trials indicated that patients with advanced-stage CML experience relapse due to development of resistance caused by point mutations within the BCR-ABL domain (notably T315I), amplification of the BCR-ABL protein, overexpression of BCR-ABL protein or the ABC transporter, P-glycoprotein (Coutre et al., 2000; von Bubnoff et al., 2002; Apperley, 2007; Tanaka and Kimura, 2008).