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:In the study of Park et al., 2005 it was proposed that IFN-γ employs the MEK/ERK signalling pathway to induce NF-κB activation in BV2-cells (Park
et al., 2005).
Category: