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:…we recently demonstrated the important role of another 89-kDa periplasmic protein localized in the invasion tip during bacterial escape from the host digestive vacuole, migration through the host cytoplasm towards the target nucleus, and invasion into the macronucleus (Iwatani et al., 2005).
Category: