Effect of fludarabine and anti-CD40 MoAb on NF-κB/Rel nuclear complexes. B-CLL cells (1 × 10⁶/mL) were incubated in 10% FCS-RPMI 1640 medium, in the absence (a) or presence of fludarabine (0.8 μg/mL) (b), MoAb G28-5 (10 μg/mL) (c), or MoAb G28-5 + fludarabine (d). After 20 hours, nuclear extracts were obtained and incubated with a ³²P-labeled κB (A) or SP-1 (B) oligonucleotide. The DNA-protein complexes were analyzed by EMSA. The SP1-normalized integrated O.D. (×10⁻²) (see Materials and Methods) of the bands 1 + 2 were: a, 1.1; b, 0.2; c, 3.9; d, 2.7.