Effects of TACI siRNA and heparitinase on APRIL- and BAFF-induced NF-κB2 and AID expression and PKA phosphorylation. B cells pretreated with control siRNA, TACI siRNA, or heparitinase (10 U/mL) were cultured with anti-BCR antibodies (anti-Igκ and anti-Igλ, 0.5 μg/mL each), CD40L (2 μg/mL), BAFF (4 μg/mL), APRIL (8 μg/mL), anti-TACI mAb (11H3; 5 μg/mL), or control mouse IgG2a (5 μg/mL) in the presence of TGF-β (1 ng/mL). Incubation times differed with individual probes: 30 minutes for NF-κB1/p65 and TACI, 6 hours for NF-κB2/p52, 72 hours for AID, and 45 minutes for PKA phosphorylation. Nuclear extracts and cell lysates were prepared and subjected to immunoblot analysis. Density of each band was analyzed (LumiVision analyzer) and was presented as relative fold of the minimum density in each panel. Data are representative of 3 independent experiments with similar results.