In the low-glucose environment created by tumor cells consuming glucose, regulatory T cells (Tregs) actively absorb lactate (LA) through monocarboxylate transporter 1 (MCT1), promoting the translocation of nuclear factor of activated T-cells 1 into the nucleus and enhancing the expression of programmed cell death protein 1 (PD-1). This evidence concerns the gene SLC16A1 and neoplasm.