Explain its normal role and why scientists refer to it as the guardian of the genome?

p53, also known as TP53 or tumor protein (EC : 2.7.1.37) is a gene that codes for a protein that regulates the cell cycle and hence functions as a tumor suppressor gene. It is very important for cells in multicellular organisms to suppress cancer. P53 has been described as "the guardian of the genome", referring to its role in confering stability by preventing genome mutation and playing roles in apoptosis, DNA repair and growth arrest in a defective cell.

(phosphoprotein or p53, functions in regulation of cell cycle in multi cellular organisms. It suppresses tumor developments, by coding for the protein which inhibit the growth and development of tumors hereby preventing cancer. Thus it is referred to as tumor suppressor gene,

Because of this role of conserving stability to the cells division by suppressing tumor and hence preventing genome mutation,

and also its inactivation leads to growth, persistence, and spread of cancer that developed it is referred to as Guardian of the genome.,