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:The inability to shut off STAT signaling properly in anterior follicle cells enables an excessive number of cells to acquire invasive properties, which can impede border cell migration (Silver et al., 2005; Starz-Gaiano et al., 2008; Yoon et al., 2011; Monahan and Starz-Gaiano, 2013).
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