ERBB3 and ovarian cancer: Because overexpression of EGFR or HER2 is not a prerequisite for a hyperactivated HER signaling, HER2-signaling is primarily hyperstimulated by TGFα or heregulin-induced EGFR/HER2 and HER3/HER2 dimers [17,18,19,169], one can’t rule out the possibility of an active HER2 signaling in ovarian cancer, even in the absence of HER2 upregulation.