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:PI(3)P is also a crucial component of autophagosomal membranes (Roberts and Ktistakis, 2013) and was recently shown to be required for actin assembly at phagophores (Mi et al., 2015).
Category: