ESR1 and breast cancer: Other signaling pathways that are implicated in several pathologies including breast cancer, are related to the nuclear receptor superfamily of ligand-dependent factors such as the estrogen receptor (ER), the retinoic acid-related orphan receptors (ROR α-γ or NR1F1-3), and the orphan receptor TAK1 (TR4 or NR2C2) (45).