MLL1 also known as KAT2A is a transcriptional coactivator that plays a crucial role in regulating embryonal and hematopoietic development, making MLL1 essential for proper cellular differentiation and proliferation. MLL1 function is particularly significant in acute myeloid leukemia, where MLL1 gene undergoes translocation with other genes, leading to oncogenic fusion proteins that disrupt normal gene regulation. MLL1 protein is involved in transcriptional regulation of various target genes, influencing processes such as cell cycle progression and apoptosis. Given MLL1′s pivotal role in gene expression and development, MLL1 is a key focus in cancer research, particularly in understanding mechanisms underlying leukemia.