p40 antibody (antibody recognizing ΔNp63 only) is an isoform of p63, is thought to function as a stem cell factor, responsible for maintaining cells in an uncommitted state with regenerative potential—a role that may be recapitulated in tumors derived from these cells.
p40 is normally expressed in the basal or progenitor cell layer of stratified epithelia (eg. squamous, urothelial, bronchial), basal cells of some glandular epithelia (eg. prostate), as well as myoepithelial cells of breast and salivary glands, trophoblasts and thymic epithelial cells. In tumor tissues, p40 expression is specific for squamous cell carcinoma.
p40 is equivalent to p63 in sensitivity for lung squamous cell carcinoma, but it is markedly superior to p63 in specificity, which eliminates a potential pitfall of misinterpreting a p63-positive adenocarcinoma or unsuspected lymphoma as squamous cell carcinoma. p40 appears to be a more reliable marker for squamous cell carcinoma.
Synthetic peptide corresponding to p40 residues within aa1-100 of p40 was used as an immunogen.
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2.Bishop JA et.al, Mod Pathol. 2012 Mar;25(3):405-15.