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:BBS4 appears to act as an adaptor that connects p150 subunit of dynein transport machinery with PCM-1 and thus assists the centrosomal recruitment of PCM-1 and its associated centrosomal proteins required for the organization of microtubule radiations from the centrosome (20).
Category: