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:The central motif sequence GARGQAGVMGFO corresponding to amino acids 394–405 has the highest binding affinity for DDR2.(27) This binding site overlaps with the binding site of another soluble collagen-binding protein von Willebrand factor (vWF) in collagen type 3,(27) and is in close proximity to a binding site for decorin on collagen type 1.
Category: