TP73 and head and neck squamous cell carcinoma: Coexpression of p63 and p73 has also been reported in head and neck squamous cell carcinoma cells, a group of tumors derived from the basal epithelia of the aerodigestive mucosa.67 These cancer cells are characterized by high levels of the ΔNp63α protein.68 Interaction studies have shown that ΔNp63α interacts directly with transcriptionally active TAp73β, and that the transcriptional and tumor suppressor activity of this p73 isoform is inhibited by overexpression of ΔNp63α.