ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: Further details were provided in a study of 250 Mexican Ph-positive CML patients, which found that 90.4% of patients expressed p210BCR-ABL1, and approximately 7% of patients with p210BCR-ABL1 expressed both isoforms (b3a2/b2a2); however, co-expression of p190/p210BCR-ABL1 was seen in only 5% of patients [46].