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:, 2006) and the circadian expression of heart mPai-1 was completely abolished in Clockmutant mice (Minami et al., 2002; Oishi et al., 2005a), these results suggest that the distal mPai-1 E-box identified here is a target for GC action and may contribute to the synchronization of Pai-1 by DEX in vivo.
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