S-Myc Background Information The Myc family of genes includes five functional members, including c-Myc, L-Myc, N-Myc, B-Myc, and S-Myc. The S-Myc gene maps to the rat chromosome 19B and encodes a 429 amino acid protein. S-Myc is closely related to N-Myc, but lacks an acidic amino-acid rich sequence commonly present in the Myc family proteins. S-Myc is also very similar to c-Myc in its ability to induce apoptosis through the caspase activation pathway. S-Myc is distinct from c-Myc in that it has tumor suppressor activity and does not require p53 to induce apoptosis. The high level of S-Myc mRNA expression in nude mice suppresses the tumorigenicity of RT4-AC tumor cells, suggesting that S-Myc acts as a negative regulator of tumor growth. S-Myc may also play an important role in the transcriptional regulation of a set of genes whose expression induces programmed cell death both in vitro and in vivo.
