PER3 and rheumatoid arthritis: Due to the apparently disturbed circadian rhythm in RA and the upregulated ARNTL2, NPAS2 but paradoxically downregulated DBP and PER3 mRNA expression after TNFα stimulations, the clock counter-regulators DEC1 and DEC2 were analyzed in resting and TNFα stimulated human synovial fibroblasts.