Given the observed increases in GSH with O3 (Fig 7A), we also examined O3-induced changes in pulmonary expression of glutathione-S-transferases (Gst), to determine whether there were likely to be obesity-related differences in the glutathionylation of targets such as lipid peroxides that are generated by O3 exposure. The gene discussed is HPGDS; the disease is obesity due to melanocortin 4 receptor deficiency.