MUC16 also known as Mucin 16, CA125 is a protein that is a member of the mucin family. MUC16 plays a critical role in protecting and maintaining the epithelial lining, particularly in ovarian cancer. MUC16 consists of three distinct domains: a carboxy terminal domain, an extracellular domain, and an amino terminal domain, which contribute to function as a tumor-associated antigen. The extracellular domain facilitates interactions with other cells and the extracellular matrix, influencing cell signaling and adhesion processes. MUC16 is predominantly expressed on epithelial cell surfaces and secreted into bodily fluids, serving as a biomarker for monitoring epithelial ovarian cancer progression. The hydrophilic nature and membrane association of MUC16 suggest involvement in various physiological processes, including immune response modulation and cellular communication, making MUC16 a significant target for both diagnostic and therapeutic applications in oncology.