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:(A) Palmitoylation of mSpi would result in membrane association at both termini, whereas mSpiCS cannot be palmitoylated and remains free at its Nterminus. mSpiAG and mSpiCSAG contain mutations that prevent cleavage by Rho (purple asterisks) (Strisovsky et al., 2009).
Category: