However, A20 IEC-KO mice were more susceptible to experimental colitis and had increased IEC apoptosis, while A20Myeol-KO mice developed rheumatoid arthritis-like symptoms due to excessive activation of myeloid cells to produce high levels of pro-inflammatory cytokines, including TNF-α/IFN-γ (223). This evidence concerns the gene TNFAIP3 and rheumatoid arthritis.