Due to its crucial function in maintaining the genomic stability, p53 has been defined ”the guardian of the genome” and, indeed, somatic alterations of TP53 gene are present in about 50% of sporadic tumors [59], conferring to p53 an important role as a biomarker for the diagnosis, tumor progression, poor prognosis, and reduced sensitivity for anticancer drugs [60]. The gene discussed is TP53; the disease is neoplasm.