We evaluated the serum level of MASPs (MASP-1 and MASP-2) in total 68 SLE patients consisting of 15 patients with biopsy-confirmed membranous lupus nephritis (M-LN), 35 patients with biopsy-confirmed proliferative lupus nephritis (P-LN), and 18 SLE patients without LN (non-LN). The gene discussed is MASP1; the disease is lobular neoplasia.