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:This result is not consistent with other reports, which indicated that increased intracellular H2O2 played an important role in arsenic trioxide-induced cell death in cervical cancer cells (20), APL cells (18), hepatocellular carcinoma HepG2 cells (24), and glioblastoma A172 cells (14).
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