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:The mitochondrial permeability transition pore (mPTP) is emerging as a critical player in neurodegenerative disease and in acute neuropathology (Martin et al., 2009; Martin, 2010a,b).
Category: