BACKGROUND OF THE INVENTION
Cysteine proteases, such as cathepsins B, L, S, and O.sub.2, have been implicated in a number of diseases, including cancer metastasis and invasion (Clin. Exp. Metastasis 1992, 10, 145-155; Cancer Metastasis Rev. 1990, 9, 333-352), arthritis (Int. J. Biochem. 1993, 25,