Positively charged rhodamine dyes (such as rhodamine esters and rosamines) are selectively localized in mitochondria, thus they are widely used for labeling mitochondria of live cells. Like JC-1, TMRM and TMRE are widely used for measuring mitochondrial membrane potential besides their selective mitochondrial staining. These two particular rhodamine esters stain mitochondria orange in fluorescence. Their spectral properties are similar to those of TRITC, making the use of TMRM and TMRE quite convenient. TMRE is slightly more hydrophobic than TMRM.