KL and neoplasm: The accumulated lactate is thought to drive tumor development, on the one hand, lactate leads to tumor acidosis which synergistically promotes tumor progress and resistance to antineoplastic drugs [45], on the other hand, the non-metabolic functions of lactate have been highlighted recently that lactate-derived lactylation of protein lysine residues (Kla) serves as an epigenetic modification to facilitate tumor malignant behaviors [31, 46, 47].