Expression levels of HPGD, COX and mPGES1 following HCQ stimulation by wortmannin, PD98059 and SB203580. The RA-FLS were serum-starved for 2 h and subsequently treated with HCQ (10 µM) for 24 h. Wortmannin (0.1, 0.5 and 1 nM), PD98059 (10, 50 and 100 µM) and SB203580 (1, 10 and 50 µM) were added 0.5 h prior to HCQ stimulation. The expression levels of (A and B) HPGD and (C and D) COX1, COX2 and mPGES1 in RA-FLS following the different treatments. RA-FLS, rheumatoid arthritis fibroblast-like synoviocytes; CON, control; HCQ, hydroxychloroquine; W, wortmannin; PD, PD98059; SB, SB203580; HPGD, 15-hydroxyprosta-glandin dehydrogenase; ACTB, β-actin; COX, cyclooxygenase; mPGES1, microsomal prostaglandin E2 synthase 1.