Iroquois Homeobox Protein 5 (IRX5)

IRX5 is a member of the Iroquois homeobox gene family. Members of this family appear to play multiple roles during pattern formation of vertebrate embryos.

Northern blot analysis detected 2 main transcripts of 2.6 and 3.9 kb, but the larger transcript did not appear to contain a closely related homeobox. IRX5 expression is not breast-specific, as it was found to be weakly expressed in adult human lung, uterus, salivary gland, and kidney. In situ hybridization demonstrated that IRX5 is differentially expressed in major mammary epithelial cell lineages and that its expression is further regulated during both the proliferative and cyclical phases of human breast development. IRX5 expression is maintained in human mammary neoplasias.