TP53 and head and neck cancer: To determine whether the endothall growth attenuation results with HFK+HPV16 (Fig. 6) could be extended to HPV16-positive head and neck cancer cell lines, we treated three cell lines with endothall: HN30, which are HPV negative and p53 wild type; SCC-104, which are HPV16 positive and contain episomal viral genomes; and SCC-47, which are HPV16 positive and contain integrated viral genomes (46).