The gene expression profile dataset GSE1919 (Ungethuem et al., 2010) was downloaded from the Gene Expression Omnibus (GEO, http://www.ncbi.nlm.nih.gov/geo/) database. The dataset contains 5 OA, 5 rheumatoid arthritis (RA) and 5 normal donors (ND) synovial tissue samples derived from a human study using the Affymetrix Human Genome U95 Array platform. In this paper, the OA and ND samples were analyzed by bioinformatics.