Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:GSH/GSSG, reduced PC/oxidised PC, and reduced Protein/oxidised Protein) can protect cells from oxidative damage (Tsuji et al., 2002), this produces an imbalance in the redox status that may lead to other unwanted effects such as changes in intracellular pH, which is, to our knowledge, an effect that has not been explored to date.
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