TAP1 and systemic lupus erythematosus: In addition to IFN inducible genes, a limited number of MHC class II were also upregulated as well as genes involved in antigen presenting capacity (TAP1, DAPP1) and genes involved in B cell survival and proliferation, such as BST2. In addition, LY6E, a biomarker of disease activity in SLE was upregulated in SLE B cells [35].