TP53 and neoplasm: Changes include the activation of proto-oncogenes (K-Ras) and the inactivation of three tumor-suppression genes: the loss of APC (chromosome region 5q21; the most common initial gene mutated in familial/inherited and sporadic colon cancer), the loss of p53 (chromosome region 17p13), and loss of heterozygosity for the long arm of chromosome 18 [18,28].