NFKB1 and cancer: Although it has been theoretically hypothesised that bortezomib abrogates the degradation of I-κB, which blocks the transcriptional activity of NF-κB, recent studies demonstrated that bortezomib elicits activation of multiple pathways in cancer cells, such as endoplasmic reticulum (ER) stress and reactive oxygen species (ROS) pathways (Fribley et al, 2004; Nawrocki et al, 2005; Obeng et al, 2006; Pérez-Galán et al, 2006; Yang et al, 2006).