TP53 and neoplasm: Like homozygous Trp53R210X mice, heterozygous mice showed a striking tumor phenotype, although with larger variation in tumor type and later onset of clinical signs compared to homozygous mice, and with frequent LOH, again in agreement with previous studies of Trp53-null and Trp53 missense knock-in mouse models [9, 10, 17, 20, 21, 23, 46].