ATF2, a transcription factor and target for ERK1/2 (and other MAPKs), was phosphorylated in response to LPS (T71) (p < 0.001) and showed a time-of-day increase in the RA group (disease state × time, p = 0.03), further adding to the previous finding that MAPK signalling is altered in the RA group by time of day. This evidence concerns the gene ATF2 and rheumatoid arthritis.