Figure 2. Retrograde transport and toxicity of Shiga toxin and ricin is increased in response to Vps11 knockdown. (A) HeLa cells were incubated with Stx concentrations ranging from 0.1 ng/ml to 100 ng/ml for 5.5 h. The toxicity in scrambled and Vps11 siRNA treated cells was analyzed by measuring the level of protein synthesis in Stx treated cells compared with control cells without toxin treatment (ctrl) (mean ± SEM, n = 4, P = 0.0118 at 1 ng/ml Stx). (B) HeLa cells were incubated with ricin-sulf2 (rs2) for 2 h in the presence of ³⁵SO₄^2- and the amount of sulfated rs2 was quantified on autoradiographs with Quantity One^® software (mean ± SEM, n = 3, sulfated rs2; *P = 0.003, glycosylated rs2; *P = 0.0316). Representative blots are depicted below the graph. (C) HeLa cells were incubated with ricin concentrations ranging from 1 ng/ml to 100 ng/ml for 3 h and the toxicity was analyzed as described for Stx in (A) (mean ± SEM, n = 3, P = 0.0299 at 1 ng/ml ricin).