TP53 and neoplasm: The p63 isoforms can be placed into two groups: the transactivation domain isoforms, which structurally resemble p53 and act as tumor suppressors, and the ΔN isoforms, which bind to p53, TAp63 and TAp73 and inhibit their function, thus acting as oncogenes.7, 8, 9 In the skin, TAp63 is required to maintain adult dermal stem cells and epidermal progenitor cells, required for wound healing and hair regeneration, in quiescence.5, 10 ΔNp63 also has an important role in the skin.