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:We have shown that, in response to water deWcit, both proteins accumulate in the soluble fraction of the cell wall, and speciWcally bind to plasma membrane vesicles, in a divalent cation-dependent manner (García-Gómez et al. 2000).
Category: