FAP and rheumatoid arthritis: However, there are certainly overlapping FAPα+αSMA+ subpopulations—in the epiretinal membranes of patients suffering from proliferative vitreoretinopathy [106], in samples of intestinal stenosis [102], in the synovial membranes of rheumatoid arthritis [105], in a human liver with cirrhosis [100], and in skin samples from patients with scleroderma [123].