Antigen Backgroundp40 (Delta Np63) is a truncated product of the p63. It is normally expressed in the basal or progenitor cell layer of stratified epithelia, basal cells of prostate, as well as myoepithelial cells of breast and salivary glands, and cytotrophoblasts in placenta, and shows a nuclear staining pattern with IHC. Among the numerous neoplasms positive for p40, squamous cell carcinomas of pulmonary and non-pulmonary origin can be identif...