The cellular migration can be related to the TNFR1 expression, since this receptor is expressed on a fraction of CD4+ T in RA patients, but not in control group; this migration is dependent on the TNF-α concentration gradient ex vivo, and blocking of TNF-α or TNFR1 expression resulted in abrogation of CD4+ T cells migration in synovial tissue [47]. Here, CD4 is linked to rheumatoid arthritis.