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 both gastric (intestinal-type) and Barrett oncogenesis, HER2 overexpression has been reported in both cancer samples and IEN, suggesting an early involvement of HER2 dysregulation in the oncogenetic cascade [4,7].
Category: