TNFSF13B and systemic lupus erythematosus: In lupus nephritis (LN), proximity extension assay proteomics identified urinary ICAM-2, FABP4, FASLG, IGFBP-2, SELE, and TNFSF13B/BAFF as markers distinguishing active LN from inactive SLE, correlating with histologic activity indices (27).