We produce evidence that junctional transport of lactate benefits tumours dually by (i) offering a pHe-insensitive route for discharging metabolic waste from glycolytic cells, and (ii) alkalizing recipient cells to levels that are generally conducive for proliferation.27, 28, 29 Our findings propose a novel, lactate-handling role for Cx43 which may be particularly critical in acidotic regions of tumours. This evidence concerns the gene GJA1 and neoplasm.