Full-length (Prtg-full) cDNA and mutant cDNA with a complete deletion of the SP region were inserted into an enhanced green fluorescent protein (EGFP) (Clontech) vector, and was then transfected into MISK81-5 cells, which is an oral squamous cell carcinoma cell line established in our laboratory [22], to characterize the intracellular localization of the Prtg protein. This evidence concerns the gene PRTG and squamous cell carcinoma.