KL and cancer: In 2019, lactate‐derived lysine lactylation (Kla) in histone proteins was identified as a new type of posttranslational modifications (PTMs).[13] Accumulating evidence suggests that protein lactylation is involved in diverse biological processes such as tumor proliferation,[14] nervous system regulation,[15] and metabolic regulation.[16] Given the enhanced glycolysis and lactate overproduction in cancer cells, the discovery of lactylation provides a new perspective on the important mechanisms of lactate function in cancer progression.