MCU and Burkitt lymphoma: Primary mouse B cells and the Burkitt lymphoma cell line Ramos were used to study functional consequences of the loss of the Mitochondrial Calcium Uniporter.<h4>Results</h4>Here, we show that mitochondrial Ca<sup>2+</sup> levels dynamically respond to cell activation, stress and metabolic cues and that mitochondrial Ca<sup>2+</sup> uptake is largely dependent on the Mitochondrial Calcium Uniporter.