A. Quantification of the mTFP/Venus fluorescence ratio of laconic (lactate sensor) showing concentration-dependent lactate uptake in HBVPs. (n=8 from 3 independent experiments. Error bars indicate the standard error of the mean (SEM)) B. Representative images showing mTFP (blue) and Venus (yellow) fluorescence in control and lactate (20mM) treated HBVPs. 