Original fingerprint [RNA arbitrarily primed (RAP)-polymerase chain reaction (PCR)] of RNA of synovial fibroblasts derived from 10 different patients with rheumatoid arthritis and six patients with osteoarthritis. Each RAP-PCR was performed in triplicate using three different RNA concentrations. Left two lanes: DNA marker. Triplicate lanes 1–10 show the RAP-PCR of the synovial fibroblasts of the 10 rheumatoid arthritis patients, and lanes 11–16 show the RAP-PCR of those of the osteoarthritis patients. The arrow indicates the differentially displayed gene fragment seen in the rheumatoid arthritis patients (434 base pairs), which was used for subsequent analysis.