MICA and rheumatoid arthritis: Taking into account the mentioned disruption of MICA-induced downmodulation of NKG2D expression reported in RA, it may be speculated that NKG2D levels are not reduced in response to the chronic expression of MICA molecules not only due to increased TNF activity, but it may also be associated with the presence of MICA-129Val variant at high-expression levels on target cells.