EP300 and rheumatoid arthritis: To further confirm whether ICAM2 affected the PI3K/AKT/p300 pathway, we knocked down ICAM2 in RA‐FLSs and found that p‐PI3K, p‐AKT and p300 levels were downregulated in ICAM2‐deficient RA‐FLSs (Figure 6O–Q).