The epithelial cells were seeded into 24-well tissue culture plates to a confluency of 50–80% prior to transfection. For RNA silencing, AGS cells were replaced by MKN-45. The cells were washed twice with serum-free cell culture medium and transfected with 25 nM ON-Target Plus SMARTpool siRNA (Dharmacon) in Opti-MEM (Invitrogen) using Lipofectamine RNAiMAX (Invitrogen) according to manufacturer's recommendations. Following an overnight incubation cell culture medium supplemented with 10% FBS was added. The cells were maintained for a further 48 h at 37°C and 5% CO2 before use in experiments for bacterial adhesion and qPCR analysis as described in the sections above. The efficiency of knockdown was determined using qPCR.