ERBB4 and breast cancer: ERBB3 is a member of the ERBB receptor tyrosine kinase family and has been found to be overexpressed in breast cancer, ovarian cancer, lung cancer, and CRC.46–49 Nrg1 serves as the principal ligand for the ERBB receptor family and predominantly interacts with ERBB3 receptors located on the cell membrane.50 The binding of Nrg1 to ERBB3 induces a conformational alteration, facilitating its heterodimerization with other ERBB family receptors (EGFR, ERBB2, and ERBB4).