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:1B) and introduced a site-specific nick in the sense strand of the EGFPcC>G reporter by transfecting reporter cells with PX462 plasmids (Ran et al. 2013b) that coexpressed Cas9D10A and EGFP-specific sgRNA (sgEGFP).
Category: