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:5B), but, interestingly, they shared conserved residues that are most notably found in the NQO1 family of eukaryotes (Chen et al., 2000; Faig et al, 2000).
Category: