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:PTOV1 can bind to flotillin-1 (Santamaria et al. 2005) and the 14-3-3 protein (Benzinger et al. 2005), which can interact with CDK1 (Chan et al. 1999).
Category: