BIRC5 and myeloid sarcoma: The regulation of mitosis and apoptosis in immune cells can be mediated by cell cycle-regulated antiapoptotic proteins, such as survivin, which is a protein encoded by the Baculoviral IAP repeat-containing 5 (BIRC5) gene, and, in RRMS patients, it has been found that the genetic polymorphisms located in this gene promote increased levels of survivin [69,70], which suggests a critical participation in the persistence of the inflammatory condition in MS patients by contributing to reduced self-tolerance [71,72].