MF4 comprises three important fields of medical science and physiology: Host Defenses, Neoplasia and Genetics. MF4 begins with an introduction to the ways the human body deals with dangerous agents that might threaten its survival. The first group of dangerous agents cause infections whose source is ultimately the external environment, although many establish themselves as part of the normal flora. The body is constructed to repel the entry and attack, and to limit, the damage caused by the infectious agents. The defense mechanisms are very complex and can cause serious disruption of the human host. The second group of agents are cancer cells of the body. These are human cells which have been disrupted, often by the changes in the genetics of the individual cells, leading to uncontrolled growth and damage to the host. The basic changes in the genetic structure which result in neoplasia, the concepts behind the damage caused, and the potential interventions make up the remainder of the Foundation.