As reported for homozygous Trp53-null and Trp53 missense knock-in mice [9, 10, 17, 20–24], homozygous Trp53R210X mice showed a remarkable susceptibility to tumor development at an early age, with lymphoma as the predominant tumor type, (79.2% in Trp53R210X/R210X mice and 57-78% in homozygous Trp53-null and Trp53Mis mice) followed by soft-tissue sarcoma (35.4% in Trp53R210X/R210X mice and 22-38% in homozygous Trp53-null and Trp53Mis mice). The gene discussed is TP53; the disease is lymphoma.