PAR4 also known as PAWR is a tumor suppressor protein that selectively induces apoptosis in cancer cells through intracellular and extracellular mechanisms. PAR4 plays a crucial role in the regulation of apoptosis, a process essential for normal tissue homeostasis and development. PAR4 is specifically expressed in cells undergoing apoptosis and is not induced by growth factor stimulation, oxidative stress, necrosis, or growth arrest, highlighting its unique function in programmed cell death. The PAR4 gene encodes a protein that features a putative nuclear localization signal and a carboxy-terminal leucine zipper, which are important for its function in the nucleus and may facilitate interactions with other proteins involved in apoptotic signaling pathways.