IgM and CD40 engagement in CLL cells promote NF-κB activity in CLL cells.

(A) Nuclear extracts were prepared upon purification of the cells (t₀), or after 4 hours of culture with media or anti-IgM, and evaluated by EMSA with a labeled probe for NF-κB binding activity. (B) Cells from another case were stimulated in culture for 4 hours prior to preparation of nuclear extracts and evaluation by EMSA. (C) To confirm the specificity of the signals for NF-κB activity, EMSA was performed using the extracts of panel B in the absence or presence of 50-fold molar excess of competitive, unlabeled Oct-1– or NF-κB–binding oligonucleotides.