Upon antigen binding in the lymphoid tissue, the receptors on the CLL surface aggregate, leading to phosphorylation of immunoreceptor tyrosine-based activation motifs (ITAMs) in the cytoplasmic tails of Igα/Igβ by the Src family kinases such as Lyn and Fyn. The gene discussed is FYN; the disease is B-cell chronic lymphocytic leukemia.