This gene encodes tumor protein p73, which is a member of the p53 family of transcription factors involved in cellular responses to stress and development. The family members include p53, p63, and p73 and have high sequence similarity to one another, which allows p63 and p73 to transactivate p53-responsive genes causing cell cycle arrest and apoptosis. The family members can interact with each other in many ways involving direct or indirect protein interactions, resulting in regulation of the same target gene promoters or regulation of each other's promoters. The p73 protein is expressed at very low levels in normal tissues and is differentially expressed in a number of tumors. The p73 gene expresses at least 35 mRNA variants due to the use of alternate promoters, alternate translation initiation sites, and multiple splice variations. Theoretically this can account for 29 different p73 isoforms; however, the biological validity and the full-length nature of most variants have not been determined.