PLA2R1 and lupus nephritis: In 2009, Beck et al. reported that M-type phospholipase A2 receptor-1 (PLA2R1) protein and anti-PLA2R1 auto-antibodies (auto-Abs) (mainly immunoglobulin [Ig]G4 isotype) were co-localized and deposited in podocytes in a majority (about 70%) of IMN cases, but not in patients with SMN, lupus nephritis or IgA nephropathy7.