Fig. 9.

(a) Shigella can directly access the cryptic progenitor cells in rabbit intestine. Shown is a rabbit intestinal tissue 12 h after inoculation with 2 × 10⁸ GFP-Shigella (green) stained with rhodamine-phalloidin (red) and TO-PRO3 (blue). (b) A model for Shigella strategy to cause cell cycle arrest via the interaction of the IpaB effector with Mad2L2. Once inside the epithelial progenitors, invaded bacterium delivers IpaB via TTSS, which interferes with the binding of Mad2L2 to Cdh1, leading to unscheduled activation of APC and subsequent Cyclin B1 degradation.³⁹⁾