CD8A and cancer: The prime function of an immune cell is to remove cancer cells from the body by cytotoxic T lymphocytes (CTL or CD8+ cells) and natural killer (NK) cells through polarized discharge of the contents of cytotoxic granules towards the target cells.2 The effector function of CTL and NK cells as well as their proliferation and apoptosis of cancer cells largely depend on Ca2+ signaling.