The Sox family are comprised of members that are related to the mammalian sex determining gene SRY. The Sox family of genes similarly contain sequences that encode for the HMG-box domain, which is responsible for the sequence-specific DNA-binding activity. Sox genes encode putative transcriptional regulators implicated in the decision of cell fates during development and the control of diverse developmental processes. The highly complex group of Sox genes cluster at least 40 different loci that rapidly diverged in various animal lineages. At present, 30 Sox genes have been identified. Members of this family have been conserved during evolution and play key roles during animal development. Some are involved in human diseases, including sex reversal. Sox-11 (SRY (sex determining region Y)-box 11) is a 441 amino acid nuclear protein expressed mainly in the nervous system. Containing an HMG box DNA-binding domain, Sox-11 may play a critical role in the developing nervous system.