TP53 and neoplasm: To determine whether LIN28 proteins are required for tumor initiation, we generated liver-specific Tp53-KO mice (Albumin-Cre; Tp53fl/fl) and Lin28a/Lin28b/Tp53–triple-KO (TKO) mice (Albumin-Cre; Lin28afl/fl; Lin28bfl/fl; Tp53fl/fl).