HSP90AA1 and prostate neoplasm: Interestingly, the in vitro formation of 3D (sphere-like) organoid structures by prostate tumor-derived cell lines was accompanied by the enhanced secretion of HSP90- and EpCAM-containing exosomes and also multiple stemness marker expression [105]; on the other hand, extracellular HSP90 appears to stimulate spheroid growth, EMT, and CSC accumulation.