TP53 and neoplasm: Liver-tumor formation was frequent in Tp53-KO mice, but was impaired in Lin28a/Lin28b/Tp53-TKO mice (Figure 1, C and D); 64% of Tp53 WT mice, 100% of Tp53 KO mice, and 62% of Lin28a/Lin28b/Tp53 TKO mice had gross tumors, and TKO tumors were smaller than tumors from Tp53-KO mice.