Promyelocytic leukemia protein (PML) is a protein encoded by the PML gene, which plays a crucial role in regulating cell growth and apoptosis (programmed cell death). It is involved in various cellular processes, including DNA repair and the response to stress. PML is known for its function in forming nuclear bodies, which are structures within the cell nucleus that help organize and regulate gene expression. In the context of acute promyelocytic leukemia (APL), a subtype of leukemia, the PML protein is often fused with the retinoic acid receptor alpha (RARA) gene due to chromosomal translocations. This fusion protein disrupts normal cell function, leading to the accumulation of immature blood cells. Understanding PML's role in APL has been essential for developing targeted therapies, such as all-trans retinoic acid (ATRA), which can help restore normal cell differentiation.