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:Since it has been shown that this modification reduces the binding activity of annexin [8], and also, that all four domains present in anxA5 are necessary for optimal binding affinity [9], it is important to ensure that the binding properties of anxA5 are not impaired by these reactions.
Category: