Dr. Parsons is a leader in establishing the importance of PTEN/PI3K pathways in cancer progression. In this presentation, he discusses the broad scope of his research into PTEN as a tumor suppressor. Dr. Parsons examines the structure and functions of PTEN, as well as the wide variety of disorders the alteration of this gene can cause. He also explores the implications for therapies in a variety of cancers, including breast and prostate cancer. In addition, Dr. Parsons discusses how PTEN and other tumor suppressor genes are transcribed by p53, and how its mutation can trigger tumor initiation or progression. A thought-provoking question and answer session follows.