Of these, p53 was discovered almost 40 years ago and still remains one of the most intensively studied tumor suppressor genes; as a consequence it shows very diverse, complex and articulated physiological functions, spanning from regulation of apoptosis, autophagy, mitochondria activity and oxygen radical homeostasis metabolism, DNA damage and repair pathways, maintenance of stem cell repertoire, as well as cell lineage determination [74–93]. The gene discussed is TP53; the disease is neoplasm.