Additionally 17/20 squamous tumors, and 2/20 for adenocarcinomas stained positively for p63 (Trp63), a protein involved in the self-renewal of stratified epithelial progenitors [22] and a frequent marker of squamous cell cancer that clusters closely with SOX2. In 14 of 20 squamous tumors, there was positive staining for both Sox2 and p63. This evidence concerns the gene SOX2 and adenocarcinoma.