NR4A1 and breast cancer: MAPKs are strongly related to breast cancer prognosis, which participate in hormone receptor modulation, response to growth factors and targeted therapies.64–66 The MAPK pathway is activated in approximately 50% of breast cancers.67 RAS mutation, which frequently observed in tumors such as pancreatic cancer and colorectal cancer,68 leading to constitutive activation of ERK1/2, is not considered as the main cause of MAPK signaling activation in breast cancer, as RAS mutation occurs in less than 5% of breast cancer cases.