NOL3(Nucleolar protein 3), also known as ARC, NOP30, CARD2 and MYP, is a protein that in humans is encoded by the NOL3 gene. NOL3 has been shown to interact with SFRS9 and Caspase 8. By genomic sequence analysis, Stoss et al. (1999) determined that the NOL3 gene, which encodes NOP30 and MYP and which they called NOP, is composed of 4 exons. The alternative 5-prime splice site that generates the 2 isoforms is located in exon 2. It is reported that expression of the ARC cDNA encoding the smaller transcript inhibited apoptosis in a dose-dependent manner when coexpressed with CASP8 but not when coexpressed with CASP9. ARC also inhibited apoptosis induced by stimulation of CD95/FAS, tumor necrosis factor receptor-1, and TRAMP/death receptor-3. Enzymatic analysis showed that ARC inhibits the enzymatic activity of CASP8. Immunoprecipitation and immunoblot analysis indicated that ARC interacts with CASP2 and CASP8 through its N-terminal death effector domain but does not interact with CASP1, CASP3, or CASP9.