Figure 2.

Pathways affecting the risk of breast cancer. The prophylactic effect of pregnancy hormones appears to act directly on the p53 protein to alter its activity. Genetic susceptibility mediated by high-penetrance cancer susceptibility genes appears to affect the integrity of the p53 gene, whereas low-penetrance modifiers may serve to alter the activity of the p53 protein. The kinases and acetylases that regulate p53 activity provide targets for chemopreventive agents.