Surprisingly, we observed little if any effect of Rac1 peptide on cartilage and joint destruction in murine arthritis, although a significant decrease in paw swelling was observed in mice when treated at the onset of disease, and a reproducible trend toward reduced paw swelling was noted in mice treated with Rac1 peptide at a more chronic phase of disease. This evidence concerns the gene RAC1 and arthritic joint disease.