Epithelial cells were infected with the EHEC WT, ΔespO1-1ΔespO1-2 double mutant or ΔespO1-1 and ΔespO1-2 single mutants, and at 1 and 3 h post-infection an active form of RhoA (GTP-RhoA) in the lysates of infected cell samples was precipitated with the Rho binding domain (RBD) of rhotekin, which only binds GTP-RhoA. The gene discussed is RTKN; the disease is infection.