BCR and chronic myelogenous leukemia, BCR-ABL1 positive: On the other hand, it is known that protein BCR (64-413) , overexpressedin Ph + cells in CML mice, is phosphorylated by the bcr/abl protein atthe tyrosine residue, thus reducing the kinase activity of the bcr/abl oncoproteinby 80% [37–40].