ACIN1 is an auxiliary component of the splicing-dependent multiprotein exon junction complex (EJC) deposited at splice junction on mRNAs, and it is a part of the ASAP complex that is recruited to the EJC during the splicing process. The ASAP complex promotes apoptosis and is disassembled after induction of apoptosis. ACIN1 is also involved in the splicing modulation of BCL2L1/Bcl-X and probably other apoptotic genes. It specifically inhibits the formation of proapoptotic isoforms such as Bcl-X(S). Furtehrmore, it induces apoptotic chromatin condensation after activation by CASP3. Finally, it regulates cyclin A1, but not cyclin A2, expression in leukemia cells. In immunohistochemistry, ACIN1 as nuclear positivity in all tissues throughout the body. References: The UniProt Consortium. Nucleic Acids Res. 47: D506-515 (2019); Nucleic Acids Res. 2016 Jan 4;44(D1):D733-45, PMID:26553804