A scaffold protein that directs CASP3 to certain substrates and facilitates their ordered degradation during apoptosis. May also play a role in mediating CASP3 cleavage of KRT18. Regulates degradation of intermediate filaments during apoptosis. May play a role in the general transcription machinery in the nucleus and might be an important regulator of the activity of GTF3C3 (By similarity). Inhibits DNA transcription in vitro. Interacts with CASP8, CASP10, KRT8, KRT18, CASP3 and FADD. Homodimerizes and heterodimerizes with DEDD2 (By similarity). Translocated to the nucleus during CD95-mediated apoptosis where it is localized in the nucleoli. Following apoptosis induction, the mono and/or diubiquitination form increases and forms filamentous structures that colocalize with KRT8 and KRT18 intermediate filament network in simple epithelial cells (By similarity). Ubiquitously expressed. Exists predominantly in a mono- or diubiquitinated form.