GADD34 (Growth Arrest and DNA Damage inducible-protein) is a regulatory subunit of PP1 (phosphatase 1) phosphatase which dephosphorylates eIF2alpha (eucaryotic initiation factor 2 alpha subunit), representing a negative feedback loop of the unfolded protein response (UPR). Moreover, GADD34 is necessary for type I interferon (IFN) production in response to viral infection in murine models. We investigate here the expression of GADD34 in systemic lupus erythematosus (SLE), in which type I IFN has an important pathogenic role.