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:2B, D) resembled those due to loss of other STAT negative regulators (Silver et al., 2005; Starz-Gaiano et al., 2008; Yoon et al., 2011; Montell et al., 2012; Monahan and Starz-Gaiano, 2013), but looked different from the phenotypes caused by misregulation of EGF or PDGF/ VEGF signaling (Duchek and Rørth, 2001; Duchek et al.
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