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:It has been reported that NF-κB activation can induce expression of Bcl-2 protein, thereby inhibit apoptosis.((33)) However, our results documented that HQH could attenuate adriamycin-induced cellular apoptosis, while NF-κB signaling was inhibited.
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