Comparisons of five gel maps for untreated normal and CF cells indicated the differential expression by 2 fold or higher of the key redox proteins thioredoxin 1 (TRX-1), Mn superoxide dismutase (SOD2), glutathione-S-transferase pi (GST-pi), peroxiredoxin (PRDX) 6, TRX dependent peroxide reductase (PRDX-1), and catalase (Figure 3, Table 1). Here, CAT is linked to cystic fibrosis.