We found that ER-α expression in RBCs from RA patients did not correlate with plasma TAC and correlated with 1) inflammatory biomarkers, i.e., ESR and CRP, 2) oxidative stress-related biomarkers, i.e., ROS/RNS and 3-nitrotyrosine (3-NT), and 3) p-ERK1/2 expression (Table 2). Here, CRP is linked to rheumatoid arthritis.