Modest effects of transient MPPβ, PARL and AFG3L2 knockdown on mitochondrial integrity. (A) Live confocal micrographs of siRNA-transfected HEK293T cells±CCCP stained with MitoTracker (MTR) Green and Deep Red (DR); Scale bar, 5 μm. (B) MTR DR/Green ratio from images as in A. N=3; *P<0.05 compared with NT siRNA. (C) Mitochondrial interconnectivity from images as in A, N=3. (D) Oxygen consumption in state 3 respiration in mitochondrial fractions from siRNA-transfected cells. Antimycin A with NT siRNA was used as a control. A.U., arbitrary unit; CCCP, carbonyl cyanide m-chlorophenyl hydrazone; MPP, mitochondrial processing peptidase; NT, non-targeting; PARL, presenilin-associated rhomboid-like protease; siRNA, short interfering RNA.