Although no statistically significant difference was observed in autophosphorylation of Lyn at Y396 in the catalytic domain that is required for full catalytic activity of this kinase between M-CLL versus U-CLL, higher levels were detected in IgG M-CLL compared with IgM U-CLL or IgM M-CLL (Figures 2C, D). This evidence concerns the gene CD40LG and B-cell chronic lymphocytic leukemia.