SORT1 and breast cancer: Indeed, GRN encoded protein, Progranulin, was shown to bind to SORT1 encoded protein, Sortilin 1, based on co-immunoprecipitation experiments performed in various mice cell lines [68–70] and in green monkey fibroblasts, and on co-expression experiments in human breast cancer cell lines [71, 72] (Additional file 7: Table S6).