ESR1 and breast cancer: Under the screening criteria of DC ≥ 60, BC ≥ 0.025, and CC ≥ 0.651, Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), RAC-alpha serine/threonine-protein kinase (AKT1), Estrogen receptor (ESR1), Mitogen-activated protein kinase 3 (MAPK3), Epidermal growth factor receptor (EGFR), Tumor necrosis factor (TNF), Mitogen-activated protein kinase 1 (MAPK1), Heat shock protein HSP 90-alpha (HSP90AA1) are the core proteins in the PPI network (Figure 5G).