ERBB2 and breast cancer: Currently, immunohistochemistry and fluorescence in situ hybridization are used to identify HER2-positive breast cancer and to decide whether a patient is eligible for HER2-targeted therapy (e.g., inhibition of HER2-triggered signal transduction by humanized antibodies, small molecules targeting catalytic activity of receptors in clinical trials, and new anti-HER2 strategies) [11].