ERBB4 and cancer: Several cancers, particularly breast, ovarian, and nonsmall cell lung cancers, present overexpression and mutation in ErbB receptors.[7] Her3 is a member of the Her complex (EGFR/HER1/ErbB1, HER2/ErbB2, HER3/ErbB3, and HER4/ErbB4) and plays an essential role in cell proliferation and survival.[8] The activation of Her3 is dependent on binding to and/or heterodimerization with other ErbB receptors,[9] which plays a critical role in the regulation of the Her signaling cascade.