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:Swi1-Swi3 are evolutionally conserved (Tof1-Csm3 in budding yeast and Tim1-Tipin in metazoan), and these proteins physically interact with Mrc1 (4, 13, 41, 45) and are known to be required for stabilization of stalled replication fork and induction of replication checkpoint (7, 31).
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