p53 is a protein that plays an important role in the regulation of cell division and thereby offers protection to the cell against malignant transformation. This is the most well-studied and most appreciated role of p53, due to which the protein is famously known as the “guardian of the genome.” It is the most studied protein in all forms of cancer research, with much of this research investigating p53’s role in tumor suppression. However, research has also shown that p53 plays a role in a wide range of other cellular functions, like serving as a biomarker for environmental pollution. Even as a tumor suppressor and transcription factor, many aspects of p53 function are still obscure, and research in the field is continually attempting to shed light on these functions. This book examines and discusses the myriad roles of p53 and different aspects of its functions. Chapters examine p53 in cancer prevention, DNA repair, gene regulation, and more.