Notably, expression of the EGR1 and FOS transcription factors, which are known to be regulated by MAPK signaling pathways, was reduced in T3SS1+ΔvopQ-infected cells compared to T3SS1+-infected cells and highly elevated by T3SS1+ΔvopS infection (Data Set S1, sheet 2) (20). This evidence concerns the gene EGR1 and infection.