Expression of fibroblast activation protein (FAP) mRNA. Synovial tissue samples were collected by orthopaedic surgery from 10 patients with end-stage osteoarthritis (OA) who underwent joint replacement or from 10 patients with destructive refractory rheumatoid arthritis (RA). (a) Quantification of FAP gene expression was determined by real-time polymerase chain reaction (PCR) as described in Materials and methods. The data are presented relative to HPRT and are graphically visualised as box-and-whisker plots. Expression of FAP gene is significantly higher in the synovial samples of patients with RA compared with OA synovial samples (p < 0.01). (b) Reverse transcription-PCR analysis of FAP, matrix metalloproteinase (MMP)-1, and MMP-13. Synovial tissue samples were collected from patients with destructive refractory RA (column A, lanes 1 to 5) or from patients with end-stage OA (column B, lanes 1 to 5). Extraction control was performed with GAPDH PCR. Positive controls (P) were fibroblasts for MMP-1, pooled breast cancer samples for amplification of MMP-13 and p53, and FAP-transfected HT1080 cells for FAP. GAPDH, glyceraldehyde-3-phosphate dehydrogenase; HPRT, hypoxanthine phosphoribosyltransferase; L, DNA ladder; N, negative controls.