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:FGF23 induces hypertrophic growth of cardiac myocytes in vitro and LVH in rodents through a direct FGFR-dependent mechanism, but independently of a-klotho, which is not expressed in cardiac myocytes (Faul et al., 2011).
Category: