Ki-67 and p16 have been combined in some studies, pointing out not only an increase of the proliferative index in malignant tumours but an inverse relationship between Ki-67 and p16 with a Ki-67 index higher in p16-weak or -negative tumours than in p16-positive tumours [16, 37, 44, 45]. The gene discussed is CDKN2A; the disease is cancer.