Because (i) plasma VC level is decreased and VC supplementation is generally recommended in CF and COPD patients and ii) VC is not endogenously produced in human but produced in mice37, our study supports the idea that C57/BL6J-βENaC-Tg-SMP30 KO mice may be one of the ideal CF and COPD models that mimic the characteristics of human patients with lower VC level. The gene discussed is RGN; the disease is cystic fibrosis.