Granzyme B also known as GZMB is a member of the granzyme subfamily of proteins, part of the peptidase S1 family of serine proteases. Granzyme B plays a crucial role in the immune response, particularly in the induction of apoptosis in target cells, which is essential for maintaining immune homeostasis and eliminating infected or malignant cells. This serine protease is primarily located within cytolytic granules of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, where granzyme B is stored as an inactive proenzyme until release during degranulation. Upon activation, granzyme B cleaves and activates caspases, such as caspase-3, caspase-6, caspase-7, and caspase-9, leading to a cascade of events that culminate in programmed cell death. The precise localization of granzyme B within cytolytic granules ensures direct delivery to target cells during immune responses, enhancing the efficiency of apoptosis induction