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:Since p47 can serve as part of both the NOX1 and NOX2 complexes in certain cells (24), we hypothesized that NOX2 may compensate for the lack of NOX1 in vivo.
Category: