Fig. 3. The effect of Rab6A-T27N on the rate at which ricin first enters the cytoplasm. Mock-transfected control cells () or cells transfected with Rab6A-T27N () for 18 hours were chilled and incubated with 100 µg/ml of ricin for an hour to bind the toxin to cell surface receptors. The cells were raised to 37°C by addition of warm medium and protein synthesis was assessed at the indicated times as described in Materials and Methods. The solid (control) and broken (transfected with Rab6A-T27N) lines were fitted to the data points by the method of least squares.