Distribution of CBFβ-SMMHC functions. Schematic representation of functional domains of CBFβ-SMMHC. The RUNX1-binding domain (RBD) and high-affinity–binding domain (HABD) mediate interaction with RUNX1. The assembly-competence domain (ACD) in SMMHC mediates dimerization and multimerization. ACD is also required for interaction with histone deacetylase HDAC8. The region located between amino acids 134 and 221 mediates interaction with p53.