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:Along this line of thought, RBL cells display both polarized and receptor-stimulated endocytic recycling (57, 58), and we show in this paper that they also express Rab13, Rab17, Rab20, and Rab25, which are all implicated in polarized transport in epithelial cells.
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