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:Since androgen stimulation could induce DNA damage in androgen-deprived prostate cancer cells (Figure 1 and 2) (4), we aimed to determine if exposure of AR-positive cells to supraphysiological levels of androgens for 6 hours (the point of maximal induction of DSBs, but absence of significant androgen mediated cell cycle progression as shown in Figure 1 and 2) could synergize with IR.
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