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:Specific formins mediate formation of contractile stress fibers (SFs), transmembrane actin-associated (TAN) lines on the dorsal cell surface that position the nucleus, filopodia at the leading edge, isotropic cortical actin networks, and actin important for mitochondrial fission (Skau and Waterman 2015; Campellone and Welch 2010).
Category: