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:In addition, EAAT2 has also been observed in microglia after facial nerve axotomy (Nakajima et al., 2001), a feature which is consistent with previous findings indicating that macrophages and microglia may acquire glutamate transporters and thus, together with astrocytes, contribute to regulate glutamate homeostasis after injury (Rimaniol et al.
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