These results agree with previous studies suggesting that the steady-state levels of active Rac are increased in ABR (and Bcr) deficient cells.40 Following infection with EPEC-∆espH/pEspHwt, active Rac1 and Cdc42 levels in the ABR shRNA treated cells were still upregulated, albeit at somewhat reduced levels compared to the uninfected cells (Figure 5d). Here, CDC42 is linked to infection.