Par-4 is a tumor suppressor protein first discovered and identified in 1993 by Dr. Vivek Rangnekar's laboratory in prostate cancer cells undergoing apoptosis. Par-4 (later also known as PAWR) is a naturally occurring tumor suppressor. Studies have indicated that Par-4 selectively induces apoptosis in cancer cells while leaving normal, healthy, cells unaffected. Mechanisms contributing to the cancer-selective action of Par-4 have been associated with protein kinase A activation of intracellular Par-4 in cancer cells or GRP78 expression primarily on the surface of cancer cells. Par-4 is downregulated, inactivated or mutated in diverse cancers. This first of two volumes will be the first on the market on the topic of Par-4, and will provide the opportunity for researchers to discuss the future direction of studies, broaden the scope of research, and contribute a more complete understanding of the molecule's structural features, key functional domains, regulation and relevant basic and clinical/translational facets.

Par-4 is a naturally occurring tumor suppressor. Studies have indicated that overexpression of Par-4 selectively induces apoptosis in cancer cells while leaving normal, health, cells unaffected. Mechanisms contributing to this cancer-selective action of Par-4 have been associated with PKA activation of intracellular Par-4 in cancer cells or GRP78 expression primarily on the surface of cancer cells. On the other hand, endogenous Par-4 sensitizes cells to the action of a broad range of apoptotic inducers acting via the extrinsic and intrinsic pathways. A number of binding partners of Par-4 have been identified and shown to regulate Par-4 function in cancer and other diseases, such as Alzheimer's and major depression. Recent studies have recognized a number of natural products, dietary supplements, synthetic molecules and FDA-approved drugs that induce the secretion of Par-4 protein to cause apoptosis in primary or metastatic tumors, one of which is in clinical trials. More than 50 different laboratories worldwide are involved in Par-4 based research of this unique protein that has progressed from the bench to clinical trials. This second, companion volume will provide a comprehensive overview of Par-4's role in cancer and other diseases. Chapters are written by leading researchers, and will be useful for a broad audience across the scientific community, particularly students and trainees, who are the next generation of scientists and clinicians to participate in new studies and discoveries on Par-4.