Multifunctional protein that is involved in the regulation of many processes including tumor suppression, apoptosis, cell cycle progression or transcription. Promotes apoptosis by favouring the activation of caspase-9/CASP9 and allowing apoptosome formation. In addition, plays a role in the modulation of histone acetylation and transcription as part of the INHAT (inhibitor of histone acetyltransferases) complex. Inhibits the histone-acetyltranferase activity of EP300/CREBBP (CREB-binding protein) and EP300/CREBBP-associated factor by histone masking. Preferentially binds to unmodified histone H3 and sterically inhibiting its acetylation and phosphorylation leading to cell growth inhibition. Participates in other biochemical processes such as regulation of mRNA nuclear-to-cytoplasmic translocation and stability by its association with ELAVL1 (Hu-antigen R). Plays a role in E4F1-mediated transcriptional repression as well as inhibition of protein phosphatase 2A. Component of the SET complex, composed of at least ANP32A, APEX1, HMGB2, NME1, SET and TREX1. Directly interacts with SET. Interacts with ATXN1/SCA1. Interacts with MAP1B. Interacts with ELAVL1. Part of the INHAT (inhibitor of histone acetyltransferases) complex. Interacts with E4F1 (By similarity). Translocates to the cytoplasm during the process of neuritogenesis. Shuttles between nucleus and cytoplasm (By similarity). Widely distributed in the central nervous system, with an abundant expression in the cerebellum. It is moderately expressed in the cerebellum on postnatal day 7 in the external granule and Perkinje cells, increases in the second postnatal week and thereafter decreases to an adult level. Phosphorylated on serine residues, at least in part by casein kinase 2/CK2. Some glutamate residues are glycylated by TTLL8. This modification occurs exclusively on glutamate residues and results in a glycine chain on the gamma-carboxyl group (By similarity). Belongs to the ANP32 family.