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:Assuming that, as mammalian frataxin, CyaY preferentially interacts with the preformed IscU/IscS complex, the addition of frataxin in reconstitution experiments would lead to uncompetitive inhibition, thus explaining the reported inhibitory effect of CyaY on Fe-S cluster formation in vitro [22].
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