FIGURE 4.

Δ32–134 PrP and Doppel also sensitize HEK cells to G418 toxicity but are less potent than ΔCR PrP. A, stably transfected HEK cells expressing yellow fluorescent protein (YFP), WT PrP, ΔCR PrP, Δ32–134 PrP, or Doppel were treated with the indicated concentrations of drug for 5 days, and viability was assayed by MTT reduction. Cell viability is expressed as the A₅₇₀ value of treated cells as a percentage of the value for untreated cells. Data points are the mean values of duplicate wells from a single experiment and are representative of at least three similar experiments. B, the expression levels of WT PrP, ΔCR PrP, Δ32–134 PrP, and Doppel were evaluated by Western blotting using anti-PrP antibody 6D11 (lanes 1–4) or an anti-Doppel antibody (lane 5). V, vector-transfected cells. Molecular size markers are given in kDa.