According to the functional characteristics of MCT1 and MCT4 and the differential regulation of hypoxia-related genes, MCT4 mediates the release of lactate by hypoxic tumor cells, while MCT1 mediates the uptake of lactic acid by normoxic tumor cells, highlighting the mutual relationship and metabolic symbiosis between cancer cells in different parts of a single tumor. This evidence concerns the gene SLC16A1 and neoplasm.