The granzyme B inhibitor, PI-9, is present in endothelial and mesothelial cells, suggesting that it protects bystander cells during immune responses.

@article{Buzza2001TheGB,
  title={The granzyme B inhibitor, PI-9, is present in endothelial and mesothelial cells, suggesting that it protects bystander cells during immune responses.},
  author={Marguerite S. Buzza and Claire E. Hirst and Catherina H. Bird and Paul Hosking and Joe Mckendrick and Phillip I Bird},
  journal={Cellular immunology},
  year={2001},
  volume={210 1},
  pages={21-9}
}
Proteinase inhibitor 9 (PI-9) is a 42-kDa human intracellular serpin present in cytotoxic lymphocytes (CLs). PI-9 is an extremely efficient inhibitor of the pro-apoptotic CL granule proteinase granzyme B and is thought to function in the cytosol of CLs to protect against apoptosis induced by endogenously expressed or released granzyme B, particularly during… CONTINUE READING