HDAC1-8 mRNA expression and correlation between TNFα mRNA and HDAC1 mRNA expressions in synovial tissues. Total RNA was extracted from total synovial tissues that were obtained from normal controls (n = 3), osteoarthritis (OA, n = 8) and rheumatoid arthritis (RA, n = 9) patients. (a) HDAC1-8 mRNA expression was analyzed by quantitative real-time PCR analysis as described in Materials and Methods. * = P < 0.05 versus OA, ** = P < 0.05 versus normal controls. (b) Correlation between TNFα mRNA expression and HDAC1 mRNA in RA synovial tissues (n = 10).