A much larger proportion of network edges represented epithelial-stromal “self-loops” in breast cancer, as compared with normal breast (Fig. 2b), and the most significant network edges in breast cancer represented epithelial-stromal self-loops in both ER-positive (Fig. 2c, Table 1) and ER-negative (Fig. 2d, Table 1) IBC networks. Here, ESR1 is linked to breast cancer.