By contrast, the cooperation of IKKβ overexpression with the lack of tumour suppressor proteins (p53 or p16 and p19) leads to the appearance of spontaneous ameloblastic odontomas in ~25% of animals, indicating that although the overexpression of IKKβ makes odontogenic epithelia prone to tumoural transformation, a concomitant lack of tumour suppressor proteins is needed for odontogenic tumour formation. This evidence concerns the gene TP53 and neoplasm.