To determine if pathological PrPSc infects cells by macropinocytosis and if internalization is necessary for conversion of endogenous PrPC to the PrPSc form, we treated scrapie susceptible N2aPK1 [12], [45] cells with a 10−5 dilution of strain RML PrPSc-infected murine brain homogenates and the macropinocytosis inhibitor EIPA. This evidence concerns the gene PRNP and scrapie.