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 recent identification of lymphatic endothelial-specific markers, such as hyaluronic acid receptor-1 (LYVE-1) [2], has greatly increased attention on how lymphangiogenesis, the growth of lymphatic vessels, is regulated in the tumor microenvironment.
Category: