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 caveolin-1 is dispensable for general biosynthetic delivery of apical membrane cargo, it appears to play a role in the surface transport of caveolin-2 (35, 43), angiotensin receptor (63), and the TRPC-1 receptor (3).
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