TNFRSF13C and systemic lupus erythematosus: BAFF is upregulated in lesional keratinocytes in individuals with cutaneous lupus erythematosus, and upregulation of BAFF/BAFF-R signaling potentially influences the biological activity of endothelial progenitor cells in systemic lupus erythematosus (SLE) (Jackson and Davidson, 2019).