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:Panobinostat also decreased the expression of T-cell–activating costimulatory receptor CD40, DC- and T-cell–activating receptor CD83 (23), and antigen-presenting molecules HLA-A/B/C (31).
Category: