Furthermore, we divided the RA patients into three groups based on their disease activities and found that lower levels of Smad7 mRNA expression in the peripheral CD4+ T cells were associated with higher disease activities and inversely correlated with serum levels of IL-6, CRP, DAS28-CRP, DAS28-ESR, Swollen joints and Tender joints in RA patients (Figures 2B, E, F, H–K). Here, CD4 is linked to rheumatoid arthritis.