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:In addition, the interdependence of PCM-1 with ciliopathy proteins, BBS4 (12,20) and CEP290, for proper subcellular localization further supports the connection between PCM-1 and the primary cilium.
Category: