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:Similarly, five putative phosphorylation sites for Pro-directed kinases were detected in Arabidopsis CYCD3;1 based on the conserved motif S/TP and three out of these five sites were located in putative PEST regions (Menges et al. 2007).
Category: