Oxonium ions at m/z 126.055, m/z 138.055, m/z 186.066, and m/z 204.087 were found in 1127, 1112, 1069, and 1118 of CF sites, respectively, corresponding to 1102 CF peptides. Supplementary Figure 2 shows MS/MS spectra of a peptide, LHNQLLPN511VTTVER from glutathione hydrolase 1 proenzyme (GGT1, UniProt: P19440) modified by CF biantennary glycans (Pep+HexNAc-Fuc, Endo F3-modified). This evidence concerns the gene GGT1 and cystic fibrosis.