For example, these pathways, known as the Notch signaling, Hedgehog signaling, KRAS signaling DN, P53 pathway, Wnt/β-catenin signaling, and Estrogen response early pathways, have been demonstrated to be classical pathways in breast cancer and participate in tumor growth, proliferation, and metastasis, as well as estrogen response regulation. Here, KRAS is linked to breast cancer.