SDC1 and breast cancer: The 11 GRGs identified in this study included PGK1, SDC1, NUP43, NT5E, IL13RA1, GCLC, CACNA1H, P4HA1, TSTA3, MXI1, and STC1. Of these genes, PGK1 (phosphoglycerate kinase 1) has been identified to promote BC progression and metastases via forming a positive feed-forward loop with HIF-1α.