Sporadic inclusion body myositis (IBM), a subtype of the idiopathic inflammatorymyopathies (IM), is resitant to conventional glucocortidoid therapy. This project focuses on the interactions between the transcription factor NF-kappaB, essential to auto-immunity, and glucocorticoids, in IM and Duchenne muscular dystrophy (DMD). DMD is another auto-immune muscle disease responsive to glucocorticoids, although the degeneration that characterizes IBM muscles, also occurs.