SLC16A1 and cancer: Generally, lactic acid is excreted by cancer cells to maintain intracellular pH balance,[49] but might also be reconverted to pyruvate (as observed in “reverse Warburg effect”) for fueling of the TCA cycle.[50] In this case, reduced ECAR is obviously not indicating reduced aerobic glycolysis, as routinely assumed in standard Seahorse assays, but caused by blocked lactate excretion due to MCT1 loss.