BCR- ABL

Bcl-2: Bcl-2 (B-cell lymphoma-related gene) is major mammalian gene that is known to inhibit apoptosis.

Bax:  Bax is a bcl-2 homolog that forms with bcl-2 and acts to accelerate apoptosis.

Bcl-x: Bcl-x is a gene in the bcl-2 family that inhibits apoptosis after trophic factor deprivation in vitro.

ABL and BCR encoding genes are normally located on chromosomes 9 and 22, respectively. The ABL gene encodes a tyrosine kinase enzyme whose activity is tightly regulated. By the Philadelphia translocation, two fusion genes are generated: BCR-ABL on the Philadelphia chromosome (abbreviated chromosome 2Z) and ABL-BCR on the chromosome 9. The BCR-ABL gene encodes a protein with deregulated tyrosine kinase activity. The presence of this protein in the CML cells is strong evidence of its pathogenetic role. The efficacy in CML of a drug that inhibits the BCR-ABL tyrosine kinase has provided the final proof that the BCR-ABL oncoprotein is the unique cause of CML.

The discovery of the Philadelphia chromosome (in Philadelphia in 1960) led to the identification in chronic myeloid leukemia (CML) cells of the BCR-ABL fusion gene and its corresponding protein.

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