TOMM20 and cancer: Confocal imaging of PRODH expression in control and treated ZR-75-1 cancer cells shows not only the exclusive mitochondrial localization of PRODH protein (with TOM20 co-localization) in control cells but also its significant loss associated with upregulation of mitochondrial GRP-75 and no change in total TOM20 mitochondrial membrane expression after 24 h of 5 mM N-PPG treatment (Fig. 2A).