PPY and rheumatoid arthritis: Cluster 1 in RA included sVCAM-1, c-Peptide, sICAM-1, Glucagon, PP, MMP9 and Insulin, while Cluster 2 included MMP1, MMP3, CRP, SAA, GLP-1, GIP-1 and Leptin, thus suggesting the markers within the two clusters might be expressed together in patients.