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:2e, Fdps-Luc, Msmo1-Luc, and Dhcr24-Luc (10 ng) were transfected into Y-1 cells along with expression plasmids of Ad4BP/SF-1 (300 ng) and transcriptionally active SREBP-2 (1-481) (100 ng)44.
Category: