ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: Dividing all the BCR-ABL1IS levels into quartiles (Fig 4B), it is clear that there is a degree of linearity between BCR-ABL1 transcript and protein levels in the CML cases examined, suggesting that the development of a standardized quantitative protein scale may represent an alternative method of rapidly evaluating disease burden in CML, albeit remaining a less sensitive technique that RQ-PCR.