Regarding the TNF-α secretion, blockage of ERK1/2 pathway completely inhibited TNF-α secretion induced by all the extracellular bacteria (EPEC, EHEC, ETEC, and EAEC) at 2 h of infection, but not those induced by the intracellular bacteria, whose inhibition were of 39 and 31% for EIEC and S. flexneri, respectively. Here, TNF is linked to infection.