Mock transfection only contained transfection reagents. Detection of the RNAi efficiency The RNA interference (RNAi) efficiency

was checked by Western-blot. The cells were harvested and lysed with RIPA lysis SB431542 cost SB202190 buffer (Thermo Scientific). One hundred μg of total proteins per well were loaded onto a SDS-PAGE gel and then transferred to a PVDF membrane for western blot detection. GST pull down assay to detect the activation of RhoA and Rac1 16-HBE cells were cultured in six T-75 flasks to reach 100% confluency. Three flasks of cells were infected with T. gondii tachyzoites at a multiplicity of infection (MOI) of 10. The other three flasks of cells were kept as uninfected control (mock). At 3 hr post-infection, the medium from mock and infected flasks was aspirated and cells were trypsinized. Mock and infected cells were lysed in RIPA lysis buffer (Thermo Scientific) with ultrasonication. For negative control, 150 μg (600 μl) of the infected cell extract were aliquoted into two experimental tubes; 60 μl of loading buffer were added to each tube to a final

concentration of 15 mM EDTA; 6 μl of GDP were added to these two tubes to a final concentration of 1.0 mM GDP and the tubes were incubated at room temperature for 15 min; the reaction was stopped by adding 60 μl of stopping buffer to each tube to a Go6983 concentration final concentration of 60 mM MgCl2. The negative control cell lysate incubated with GDP, and 150 μg (600 μl) total protein from the lysate of infected, uninfected cells and T. gondii tachyzoites were added to 30 μg reconstituted GST-tagged Rhotekin-RBD protein on colored agarose beads for RhoA (Cytoskeleton Inc) or GST-tagged PAK-PBD protein bound colored

agarose beads for Rac (Cytoskeleton Inc) respectively, and incubated at 4°C with rotating overnight. The beads were washed with PBS for 3 times. 25 μl protein loading buffer was added to each group of beads and boiled for 5 min then sediment at 12000 rpm for 1 min, the supernatant was used for SDS-PAGE. At the same time, 150 μg of total protein from the lysates of of infected and uninfected cells and the T. gondii tachyzoites were used for SDS –PAGE, and actin in each group was detected via western-blot and used as the equal protein loading control for the GST pull down assay. Western-blot reagents Primary antibodies: monoclonal rabbit anti-human RhoA antibody (Cell Signaling) and polyclonal rabbit anti-human Rac1 antibody (Abcam) were used in 1:1000 dilutions; β-actin was detected for loading control with monoclonal mouse anti-human anti-actin antibody (Cell Signaling) in 1:5000 dilutions. Secondary antibody: polyclonal sheep anti-mouse IgG-HRP antibody (Abcam) and polyclonal goat anti-rabbit IgG-HRP antibody (Abcam) were used in 1:3000 dilutions. ECL Western Blotting detection reagent was purchased from Pierce. Immunofluorescence for endogenous RhoA and Rac1 after T. gondii infection 16-HBE cells were grown on coverslips to 80% confluence.