The redox-sensitive proteins were identified in Arabidopsis cells under the treatment of salicylate or flg22 (a peptide from bacterial flagellin) using OxiTRAQ method. Proteins were extracted from cell samples in the presence of NEM to block free thiols. Reversibly oxidized thiols were reduced by DTT and then tagged with biotin-HPDP. After trypsin digestion and affinity purification of the biotinylated peptides, the different samples were labeled with different iTRAQ reagent and then pooled together. Peptides were identified and quantified by tandem MS. In parallel, total protein abundance was determined by regular iTRAQ assay.