The present invention is based on the discovery that .zeta.PKC expression is increased in the tissues of arthritis patients as compared to normal individuals. Accordingly, the present invention provides methods of diagnosing, prognosing, and monitoring the course of arthritis in a patient based on increased .zeta.PKC gene expression in arthritic tissue. The present invention further provides compounds that inhibit the expression of .zeta.PKC for use as remedies in the treatment of arthritis, including, but not limited to, inhibitory polynucleotides and polypeptides, small molecules, and peptide inhibitors. In addition, the present invention provides pharmaceutical formulations and routes of administration for such remedies, as well as methods for assessing their efficacy.