Although glucocorticoids are know to activate the pathway by opposing the suppression of the transcription of proteasome α-subunits by nuclear factor-κB (NF-κB) (Du et al, 2000) other factors may be involved, since chronic excessive glucocorticoid production, as occurs in Cushing's syndrome, does not increase proteasome expression (Ralliere et al, 1997). Here, NFKB1 is linked to Cushing syndrome.