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:Although the yeast studies provide evidence that NHR-64 is a transcriptional activator, nuclear receptors may also act as repressors, depending on their interactions with ligands, corepressors, or binding partners [26,27].
Category: