Scrapie infection affects cell proliferation. Cell proliferation was evaluated in ScGT1 and GT1 cells, pre-treated for 6 days with quinacrine (1 μM) and Fab D18 (50 nM), over 4 days by means of MTT assay. Prion infection inhibits cell proliferation and both treatments seem to have no effect on it. Cell growth rate was calculated as described in Materials and Methods. All data come from three independent experiments performed each one in 5 replicates; they are expressed as mean value ± SD. Statistics were performed using Student's T-test, *** P < 0.001.