BCR and B-cell chronic lymphocytic leukemia: Chronic lymphocytic leukemia (CLL) is a lymphoproliferative malignancy mediated through B cell receptor (BCR) signaling and resistance to apoptosis due to overexpression of B cell lymphoma 2 (Bcl-2), resulting in the accumulation of mature CD5+, CD19+, CD20+, CD23+ functionally incompetent B cells in peripheral blood, bone marrow, lymph nodes, and the spleen [1,2].