In a later relevant publication [104], secreted HSP90 was characterized as a modulator of the CSC phenotype’s heterogeneity in prostate cancer: The extracellular HSP90 expression was correlated with upregulation of stemness-associated markers and the EMT effector Snail, while promoting both the self-renewal and spheroid growth and drug resistance in prostate CSCs. This evidence concerns the gene SNAI1 and Familial prostate cancer.