Hsp90 inhibitor treatment reduces the proliferative fraction in CD45RO-positive memory as well as CD45RO-negative naive CD4+ and CD8+ T cells. (A) Separation of CD45RO-positive and CD45RO-negative T cells and setup of 4 separate MLRs. (B) Reduction of CFSEdim proliferating cells of the MLRs shown in panel A by Hsp90 inhibitor treatment.