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:This strong secretion and accumulation in the extracellular matrix of all cell types under low water availability denotes that these PRPs may be involved in the maintenance of cellular integrity (Millar et al. 1992; García-Gómez et al. 2000; Murphy et al. 2002).
Category: