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:…and may reflect another potentially important link between oxidative stress and excitotoxicity via the microglial antiporter system Xc
2 (Sato et al., 2002), releasing cytotoxic levels of glutamate into the interstitial compartment to replenish intracellular cystine to maintain the…
Category: