PECAM1 and breast neoplasm: Our results corroborate with the clinical value of TZM efficacy, since HER2+ breast tumors have been shown to be more responsive in comparison to that of HER2+ ovarian tumors.[36, 37] Although, we observed a high vascularity (anti‐CD31 staining) and comparable collagen content in AU565 versus XTM tumors, dark quencher FRET data clearly shows that tumors (XTM and AU565) with similar biological origin show similar drug binding.