RUNX1 (also known as AML1, CBFA2, and PEBP2αB) is a member of the core binding factor (CBF) family of transcription factors. RUNX1 is involved in hematopoiesis and is frequently targeted in human leukemia by chromosomal translocations that fuse the DNA-binding domain of RUNX1 to other transcription factors and corepressor molecules. Chromosomal translocations involving the RUNX1 gene are associated with several types of leukemia including M2 AML. Mutations in RUNX1 are implicated in cases of breast cancer.