In this study, we aimed at investigating the consequences of p53 reactivation by Pep3, a peptide inhibitor of the MDM2/MDM4 heterodimerization (14), on the immune response in a model of solid cancer, i.e., thyroid carcinoma that frequently occurs in association with thyroid autoimmunity (22, 23). The gene discussed is MDM2; the disease is autoimmune thyroid disease.