HSP90B2P and neoplasm: DC and tumor-derived exosomes also express a large number of major histocompatibility complex class I molecules (MHCI) and tumor markers, such as heat shock proteins (HSP), which are involved in antigen presentation and stimulation of T cells and have been shown to trigger CD8 + T cell-dependent anti-tumor responses in vitro and in vivo (Li et al. 2006).