The hallmark of this disease is the presence in all leukemia cells of a reciprocal translocation termed t(9; 22)(q34; q11) resulting in a chimeric bcr-abl (e1a2 breakpoint) fusion gene that encodes a 190 KD protein (p190) with constitutively active tyrosine kinase activity that can alter multiple signaling pathways, contributing to tumor growth and proliferation. Here, BCR is linked to leukemia.