BCR Protein

BCR (also known as breakpoint cluster region) encodes a phosphoprotein that has serine/threonine kinase activity (1). The human c-ABL oncogene is translocated from chromosome 9 to a region on chromosome 22 (associated with BCR) in chronic myelocytic leukemia. In classical t(9;22) translocation, as observed in chronic granulocytic leukemia (CGL), a hybrid DNA unit is produced comprising the BCR gene product plus the translocated c-ABL gene from chromosome 9. The BCR-ABL hybrid protein (p210) is formed that displays increased tyrosine kinase activity. A similar DNA rearrangement of the p210 protein is also found in cases of Philadelphia-positive acute lymphoblastic leukemia (ALL) (2).