MDM2 and cancer: The ARF-MDM2-p53 pathway (commonly referred to as the p53 pathway) has become the focus of many investigations due to its importance in tumor suppression, as shown by its genetic inactivation in more than half of human cancers and its functional impairment occurring in most of the remaining cancers, suggesting the reactivation of p53 as a treatment option that is potentially effective for a wide range of human cancers [34,87,88,89].