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:…0.1-1 µg/ml IgG) followed by fluorescent secondary antibody, both diluted in 4% BSA in TBST. α-Tubulin was detected with mouse monoclonal DM1α (Sigma Chemical Co, St Louis, MO). p60 katanin was detected with an affinity-purified anti-human p60 rabbit polyclonal antibody (McNally and Thomas, 1998).
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