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:Indeed, it has been reported that venom toxin affects type 1 myofibers, in which Arpp/Ankrd2 tends to be expressed (Tsukamoto et al. 2002), more than type 2 myofibers (Gutierrez and Ownby 2003).
Category: