Conversely, in triple-negative breast cancer cell lines, the downregulation of MCU caused a reduction in mtROS, HIF1α levels, cell migration, invasion and inhibited metastasis to the lung in xenograft experiments (Tosatto et al., 2016), suggesting that although mtCa2+ overload is pro-apoptotic, it is likely beneficial for invasion and metastasis of cancer cell clones that have evaded apoptosis. Here, MCU is linked to cancer.