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:MDZ is predominantly metabolized to 10-hydroxy-MDZ and 4-hydroxy-MDZ by CYP3A1 and CYP3A2 in rats (Kobayashi et al. 2002); thus, it has been used as a selective CYP3A substrate (Turpeinen et al.
Category: