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:recently an elegant study in a mouse model lacking cone Pde6c showed that cones expressed the rod photoreceptor Pde6a/b subunit proteins and that these subunits were used instead for cone phototransduction.(32) Therefore, the expression of rod phototransduction genes in FACS Tg(TaCP:EGFP) wild-type and mutant cones was examined.
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