BCR and B-cell chronic lymphocytic leukemia: The principal factors driving CLL pathogenesis, other than proliferation mediated through BCR signaling [7], are interaction with the microenvironment and resistance to apoptosis due to overexpression of B-cell lymphoma 2 (BCL2), primarily driven by the loss of regulatory microRNAs (miR-15a and miR-16-1) due to chromosome 13q14 deletion [8].