NAMPT mutants reduce the activation of NF-κB pathway.A, representative Western blot analysis of phospho(p)-p65 in healthy donor macrophages (n = 5) upon treatment (20 min) with wildtype NAMPT (WT) or the α-loop triple mutant K(68>73)A and β-loop full mutant K/R(42>51)A (100 ng/ml, 20 min). On the right, the histogram represents cumulative densitometric analysis of p-p65 in five different preparations of macrophages. Actin was used as loading control. B, histogram showing mRNA expression levels of IL1B in macrophages (n = 5) treated with indicated NAMPT variants (100 ng/ml, 6 h). Data were expressed as mean ± SEM. Paired t test was used to calculate statistical significance. ∗ p< 0.05, ns: not significant. UN, untreated condition.