ErbB

The ErbB family of proteins contains four receptor tyrosine kinases, structurally related to the epidermal growth factor receptor (EGFR), its first discovered member. In humans, the family includes Her1 (EGFR, ErbB1), Her2 (ErbB2), Her3 (ErbB3), and Her4 (ErbB4). The gene symbol, ErbB, is derived from the name of a viral oncogene to which these receptors are homologous: erythroblastic leukemia viral oncogene. Insufficient ErbB signaling in humans is associated with the development of neurodegenerative diseases, such as multiple sclerosis and Alzheimer's disease,^[1] while excessive ErbB signaling is associated with the development of a wide variety of types of solid tumor.^[2]

ErbB protein family signaling is important for development. For example, ErbB-2 and ErbB-4 knockout mice die at midgestation leads to deficient cardiac function associated with a lack of myocardial ventricular trabeculation and display abnormal development of the peripheral nervous system.^[3] In ErbB-3 receptor mutant mice, they have less severe defects in the heart and thus are able to survive longer throughout embryogenesis.^[3] Lack of Schwann cell maturation leads to degeneration of motor and sensory neurons.^[3] Excessive ErbB signaling is associated with the development of a wide variety of types of solid tumor. ErbB-1 and ErbB-2 are found in many human cancers, and their excessive signaling may be critical factors in the development and malignancy of these tumors.^[2]