While Hoogenraad’s group described a DDIT3 (DNA damage-inducible transcript 3 protein)/CHOP-10-dependent UPRmt induced by the overexpression of a truncated form of a mitochondrial matrix enzyme [77], Germain and colleagues reported a CHOP-10-independent UPRmt model in which protein aggregates accumulated within the internal membrane space (IMS) when a mutant (catalytically inactive enzyme) form of endonuclease G (N174A) was overexpressed in breast adenocarcinoma MCF-7 cells [78]. This evidence concerns the gene DDIT3 and breast adenocarcinoma.