In cells exposed to toxic agents such as CHX and actinomycin D, mitochondrial hyperfusion is mediated through long-form optic atrophy 1, SLP-2 and Mfn1.12 Enhanced mitochondrial fusion activity was shown to be obtained by Mfn2 that protects against cold stress-induced cell injury.35 In hypoxia conditions, some cancer cells exhibited an enlarged mitochondrial phenotype partly mediated through Mfn1.36 All these results clearly indicate that mitochondrial dynamics proteins are deeply involved in cellular adaptation process to different stresses. The gene discussed is MFN2; the disease is cancer.