Granulysin (GNLY) is a protein expressed in most mammals which functions as an antimicrobial peptide released by killer lymphocytes in cytotoxic granules. It is a pore-forming peptide, as it can puncture a microbial cell wall, allowing for other death-inducing enzymes to enter the microbe and cause microptosis. GNLY is inhibited by cholesterol, and is most effective in helping to kill cholesterol-deficient microbes.