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:We compared the activity of this construct with those of wild-type Tx NS1 and PR(1-80)Tx(81-230) in the Mx1 and SV40 promoter-driven reporter assays and found a reversal of the inhibitory activity, very similar to the effect of Tx(CPSFmut) (Fig.
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