Most biological functions in the MCF7 network are controlled by the PIK3R1 gene, and many other pathways, including apoptosis, ErbB, JAK–STAT, HIF-1, the control of the actin cytoskeleton, TNF, cancer-related pathways, TCR, BCR, and TLR signaling pathways, may also be related to breast cancer. This evidence concerns the gene PIK3R1 and cancer.