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:Phosphorylation of C/EBPβ inhibits expression of IL-17 downstream target genes, thus GSK3β negatively regulates IL-17 signaling through phosphorylation of C/EBPβ (20).
Category: