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:Apigenin inhibits the expression and transcriptional activity of HIF-1a by modulating several pathways [127– 129] or by inhibiting CK2 activity [61, 130] in different cancer cell lines.
Category: