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:Another group reported that the 118T9 10 repeat was associated with higher reporter gene expression in HepG2 liver cells (Yamanaka et al., 2004), and this variant was recently linked to higher incidence toxicity and increased response to irinotecan in cancer patients.
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