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:…Actin to Protect Nuclei during Confined Migration and Promote Metastasis, Cell (2016), http://dx.doi.org/10.1016/j.cell.2016.10.023
The regulation and localization of actin nucleation factors are likely critical for specifying the function of actin structures in cells (Skau and Waterman 2015).
Category: