Abe et al. reported a patient with systemic lupus erythematosus who developed macrohematuria and massive proteinuria with pathological formation of fibrous crescents after seroconversion of MPO-ANCA, and suggested that tacrolimus might be a useful immunosuppressant for treating patients with progressive LN with MPO-ANCA [20]. The gene discussed is MPO; the disease is lobular neoplasia.