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 levels of ROS and RNS and the imminent mitochondrial membrane potential change activate themitochondrial permeability transition pore (mtPTP), mtKATP, and mtKCa dissipating membrane potential and releasing all ROS and RNS [21, 23, 33, 64, 100, 101, 107–118].
Category: