Similar to stromal cells of the oral mucosa, no basal expression of NOD2 is detectable in Rheumatoid Arthritis Synovial Fibroblasts (RASFs), with NOD2 mRNA expression in these stromal populations only detectable after stimulation with POLYI:C, LPS, or TNFα (16). This evidence concerns the gene NOD2 and rheumatoid arthritis.