Nulp1 (nuclear localized protein 1), also known as TCF25 (transcription factor 25 (basic helix-loop-helix)), Hulp1 or FKSG26, is a 676 amino acid protein that plays a role in cell death. A member of the TCF25 family, Nulp1 utilizes its C-terminus to mediate transcriptional repression of SRF in vitro, and interacts with XIAP. Nulp1 localizes primarily to the nucleus but is also found in cytosol. Widely expressed, Nulp1 is found at high levels in embryonic brain and adult heart. The gene encoding Nulp1 maps to human chromosome 16q24.3, which encodes over 900 genes and comprises nearly 3% of the human genome. The GAN gene is located on chromosome 16 and, with mutation, may lead to giant axonal neuropathy, a nervous system disorder characterized by increasing malfunction with growth. The rare disorder Rubinstein-Taybi syndrome is also associated with chromosome 16, as is Crohn s disease, which is a gastrointestinal inflammatory condition.