The epidermal growth factor receptor (EGFR) kinase family consists of four receptors [ErbB1/EGFR, ErbB2/human epidermal growth factor receptor (HER) 2, ErbB3, and ErbB4] that play a crucial role in cell proliferation, differentiation, and motility and may lead to cancer development. The gene discussed is ERBB4; the disease is cancer.