HAT1 (histone acetyltransferase 1) is a multifunctional acetyltransferase with both canonical and emerging noncanonical roles. Canonically, HAT1 catalyzes acetylation of newly synthesized histone H4 and H2A in the cytoplasm, facilitating their nuclear translocation and replication-coupled chr2 assembly 1. Beyond acetylation, HAT1 functions as a succinyltransferase, modifying histone H3 at K122 and non-histone proteins like PGAM1 to enhance glycolytic flux in cancer cells 2. Recently discovered functions include lactyltransferase activity—HAT1 catalyzes RPA1 lactylation to promote homologous recombination and ferroptosis-related processes 34—and methacryltransferase activity regulating histone crotonyl-CoA-derived modifications 5. HAT1 also recruits with P300 to supply acetyl-CoA for histone acetylation essential for early embryonic development 6. Disease relevance spans multiple cancer types (liver, pancreatic, cholangiocarcinoma, nasopharyngeal, lung adenocarcinoma) where elevated HAT1 promotes tumorigenesis, plus viral infections (hepatitis B, HIV), inflammatory diseases (psoriasis, atherosclerosis), and infertility 127. HAT1 represents a promising therapeutic target, with potential interventions including RNA interference, small-molecule inhibitors, and combination approaches.