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:As shown by previous studies, miR-503 can function as a tumor suppressor, which is well reflected in the present study that showed lower expression of miR-503 was strongly correlated with higher tumor burden of GC.(8,9) Moreover, our results showed negative correlations between miR-503 expression and serum CEA level, which may be to some extent a good explanation for the potential mechanism of miR-503 in GC.
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