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:CYLD was catalytically deficient when tested with TRAF2/ 6 as substrates (4); and consistently, it increased IkBaphosphorylation and NF-kB gene reporter function (Supplementary Fig.
Category: