MAPT and supranuclear palsy, progressive, 1: Group 1 was cultured in 100% medium (control), group 2 in 75% medium and 25% tau-immunodepleted PSP brain soluble protein extract (Tau −ve) and group 3 in 75% medium and 25% mock immunodepleted (thus, tau-containing (Tau +ve)) soluble PSP brain extract.