The BCR gene (BCR is the acronym for breakpoint cluster region) is a human gene located on the long arm of chromosome 22 (22q11.23) and has 23 exons. The physiological function of the BCR gene product is not yet known. The encoded protein has serine/threonine kinase activity and is a GTPase-activating protein for protein p21rac (renal carcinoma antigen NY-REN-26).
Two mRNA variants of the BCR gene have been found, encoding different isoforms. The BCR gene, together with the ABL1 gene, is involved in the reciprocal translocation t(9;22)(q34;q11) leading to the Philadelphia chromosome.