This family consists of the amino termini of proteins belonging to the caudal-related homeobox protein family. This region is thought to mediate transcription activation. The level of activation caused by mouse Cdx2 is affected by phosphorylation at serine 60 via the mitogen-activated protein kinase pathway. Caudal family proteins are involved in the transcriptional regulation of multiple genes expressed in the intestinal epithelium, and are important in differentiation and maintenance of the intestinal epithelial lining. Caudal proteins always have a homeobox DNA binding domain (pfam00046).