SOD1 and scrapie: Another study reported that intramuscular or intraperitoneal inoculation of spinal cord homogenates from endstage SOD1G85R mice that contained SOD1 aggregates did not transmit SOD1 aggregation to the CNS or peripheral tissues of recipient mice.168 It is noteworthy that the SOD1 aggregates were found to be highly sensitive to protease degradation, which is not the case for highly transmissible species, such as the scrapie isoform of PrP.