Analysis of likely transcriptional regulators of 06:00 and 18:00 LPS-regulated genes in RA identified a number of candidate transcription factors, including RXRa (06:00) and CREB1 (18:00) (Additional file 7: Figure S4A-C), both targets for PKA, which we find is time of day regulated in RA (Fig. 3f). This evidence concerns the gene CREB1 and rheumatoid arthritis.