Levels of all supersulphides were much lower in Cars2+/− mice than in WT mice, however, and the levels of only one oxidized persulphide, i.e., GSSSG, were inversely related (increased) in a time-dependent fashion, although the simple disulphide GSSG was not appreciably affected in the COPD model (Fig. 7a and Supplementary Fig. 16). Here, CARS2 is linked to chronic obstructive pulmonary disease.