In cervical carcinoma and head and neck squamous cell carcinoma cell lines, cidofovir reduced E6 and E7 expression, induced P21, P53, and pRB accumulation, promoted the cell cycle arrest, reduced cyclin A, induced antiproliferative activity, triggered programmed cell death and radio-sensitized HPV-positive cells [243,244]. The gene discussed is TP53; the disease is cervical carcinoma.