CGNs expressing PrP are slightly more resistant to cell death induced by potassium/serum deprivation. CGNs cultured from Prn-p0/0and Prn-p+/+ mice were cultured in K25+S medium for 7 days, after which they were transferred to K5-S medium for the designated times. Cell viability was assessed by measurement of calcein fluorescence on a microplate fluorimeter. Fluorescence values in K5-S medium are expressed as a percentage of those in K25+5 medium at each time point. Data represent the mean ± SEM for at least two independent experiments. * p < 0.05, Prn-p+/+ vs. Prn-p0/0.