As expected, the RA synovium had a significantly higher immunosignal intensity (Fig. 1a) and a higher fraction of PKM2-positive stromal cells than the OA synovium (mean 72.9 ± 6.3% vs. 47.5 ± 8.7%, p = 3.06 × 10–6; Fig. 1b). The gene discussed is PKM; the disease is rheumatoid arthritis.