ALX1 is a 326 amino acid protein specific to cervix and cartilage tissues. As well as having a homeobox domain, ALX1 also contains an OAR domain, which has been suggested to be important for DNA binding or protein-protein interactions and transactivation. First characterized from a rat chondrosarcoma tumor cell line, ALX1 is a homeobox transcription factor that regulates downstream target genes and has specifically shown to act as a transcriptional repressor for rat prolactin in vivo. Homozygous ALX1 deficient mice are born with acrania and meroanencephaly, suggesting ALX1 function in the development of the neural tube. It has also been suggested that ALX1 cooperates with ALX4 in limb development and craniofacial bone formation.