As the DA.Ncf1E3 congenic rats carry the arthritis-protecting variant of Ncf1, one might speculate that the effect caused by the functional Ncf1 is to generate a resistance to the effect from induction of Ass, Cxcl9 and Mmp12 genes, which might otherwise contribute to the development of arthritis. The gene discussed is MMP12; the disease is arthritic joint disease.