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:In contrast, Bork et al. (2010) observed that except for some genes such as homeobox genes, methylation patterns were maintained throughout long-term culture of BM-MSCs, showing different results than those in our present study.
Category: