An enzymatically active NAMPT is overexpressed by CLL cells. (A) Box plot showing expression levels of NAMPT mRNA in B lymphocytes from CLL patients (n = 45) or HDs (n = 10). (B) Western blot analysis of NAMPT protein expression in CLL (n = 9) or HD (n = 9) B lymphocytes. A FLAG-tagged rNAMPT was used as internal control. (C-E) Box plots representing NAMPT activity expressed as nmol/hour/mg of protein (C), NMN and NAD intracellular concentration (nmol/mg) (D), and NAD/NMN ratio (E) in B lymphocytes from CLL patients and HDs. (F) qRT-PCR analysis showing expression of NAMPT mRNA in purified CLL lymphocytes cultured with the indicated stimuli (24 hours). When indicated, cells were pretreated with ibrutinib (10 µM, 30 minutes). (G) Purified CLL cells activated as indicated in panel F were lysed, and iNAMPT expression levels determined by western blot. Cumulative results (n = 8) are shown in the box plot.