Tumor start‐up: mitochondrial fusion makes it happen

Whether changes in cellular metabolism precede tumor formation and trigger malignant properties or simply serve as a bioenergetic adaptation of cancer during disease progression remains debated. Bonnay et al (2020) now show that a metabolic reprogramming toward increased oxidative phosphorylation is required for irreversible cell immortalization and subsequent tumor formation. Graphical Abstract Recent work reports aberrant mitochondrial fusion and increased oxidative phosphorylation as potent metabolic drivers of brain tumors in Drosophila.