WT and Mfn2 KO cells were transfected with plasmids encoding: GFP and the indicated combination of non-targeting siRNA (siCT), siRNA targeting MCU (siMCU), ChiMERA or control (indicated as WT or Mfn2 alone) plasmids. (U) cell respiratory control ration and (V) spare respiratory capacy were calculated (n=3 independent experiments). Data are presented as mean ± SEM. 