Papillomaviruses have been associated with the development of cervical cancer, penile cancer[40] and oral cancers.[41] An association with vulval cancer and urothelial carcinoma with squamous differentiation in patients with neurogenic bladder has also been noted.[42][43] There are cancer causing papillomavirus genome that encodes two small proteins called E6 and E7 that mimic cancer causing oncogenes. The way they work is that they stimulate unnatural growth of cells and block their natural defenses.