The gene encoding the Mixed-Lineage Leukemia (MLL) proteins is located on chromosome 11q23. Chromosomal translocations involving band 11q23 result in rogue activator proteins that are associated with approximately 10% of patients with acute lymphoblastic leukemia (ALL) and 5% of patients with acute myeloid leukemia (AML). Most patients affected are less than 1 year of age. MLLT11, also known as mixed-lineage leukemia translocated to 11 or AF1q, is a 90 amino acid MLL fusion partner. Based on the expression patterns of MLLT11, it is thought that MLLT11 plays a role in leukemogenesis and, specifically, the progression of acute monocytic leukemia (AML). Also, expressed in embryonic brain cortex, MLLT11 is upregulated during neuronal differentiation and is thought to play a role in the development of the central nervous system. Finally, MLLT11 has been shown to be differentially expressed in highly metastatic cells, in comparison with non-metastatic parent cells. Such findings suggest a role of MLLT11 in tumorigenesis.