Dr Dan Guerra reveals that serine protease inhibitors (Serpins) are endogenous proteins that block protease-mediated metastasis and cancer associated fibroblast activation in some tumor microenvironments but not all. The myriad 'labyrinth' interactions among cytokines , proteases, protease inhibitors and the dysregulation of the T-lymphocytic immune response obtains a confounding pharmacotherapeutic anisotropy.