ERBB2 and breast cancer: Mutations of EGFR have been identified as a cause of non-small-cell lung cancer (NSCLC) [69], overexpression of HER2 is associated with breast cancer [70], and mutations of KIT (V-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog) are implicated in gastrointestinal stromal tumours [71].