ERBB2 and breast cancer: Further, we used TMRE in a separate study to image mitochondrial membrane potential (MMP) as an oxidative phosphorylation surrogate and a fluorescent glucose analog 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxyglucose (2-NBDG) in an in vitro model of human epidermal growth factor receptor 2 (HER2)-positive breast cancer following HER2 oncogene withdrawal [21].