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 roughly 4-fold enhanced DNA methyltransferase activity conferred by Dnmt3amERe, which is reminiscent of the finding that the methylation-status of the vast majority of CpG islands in SV40-transformed human fibroblasts was unaffected despite 50-fold overexpression of Dnmt1 (Feltus et al. 2003).
Category: