Phosphorylation of ErbB4 on tyrosine 1056 is critical for ErbB4 coupling to inhibition of colony formation by human mammary cell lines.

In many studies, ErbB4 expression in breast tumor samples correlates with a favorable patient prognosis. Similarly, ErbB4 signaling is coupled to cellular differentiation and growth arrest in a variety of model systems. However, in some studies, ErbB4 expression in breast tumor samples correlates with poor outcome.

A constitutively active ErbB4 mutant inhibits drug-resistant colony formation by the DU-145 and PC-3 human prostate tumor cell lines.

ErbB4 (HER4) is a member of the ErbB family of receptor tyrosine kinases, a family that also includes the Epidermal Growth Factor Receptor (EGFR/ErbB1/HER1), Neu/ErbB2/HER2, and ErbB3/HER3. Several groups have hypothesized that signal transduction by the ErbB4 receptor tyrosine kinase is coupled to differentiation, growth arrest, and tumor suppression in mammary and prostate epithelial cells. In this report we demonstrate that a constitutively active ErbB4 mutant inhibits the formation of drug-resistant colonies by the DU-145 and PC-3 human prostate tumor cell lines.

Constitutively active ErbB4 and ErbB2 mutants exhibit distinct biological activities.

ErbB4 is a member of the epidermal growth factor receptor(EGFR) family of tyrosine kinases, which includes EGFR/ErbB1, ErbB2/HER2/Neu, and ErbB3/HER3. These receptors play important roles both in normal development and in neoplasia. For example, deregulated signaling by ErbB1 and ErbB2 is observed in many human malignancies.