TG2 is overexpressed in human RA lesions (Weinberg et al. 1991), and the presence of active TG2 substantially increases severity of disease in the CIA model (Dzhambazov et al. 2009) whereas a virally transduced localized knockdown of TG2 appears to alleviate joint destruction (Lauzier et al. 2012). Here, TGM2 is linked to rheumatoid arthritis.