Abstract
Helicobacter pylori type IV secretion system injects the oncoprotein CagA into epithelial cells to drive carcinogenesis. In this issue of Cell Host & Microbe, Tegtmeyer et al. (2017) show that a secreted bacterial protease disrupts apical-junctional complexes, paving the way for H. pylori to access the basolateral compartment and trigger pathogenesis.