POU5F1 and prostate cancer: Furthermore, it has been observed that some changes in the tumor environment such as hypoxia, may induce, through HIF (hypoxia inducing factor) generation, the reprogramming of prostate cancer cells and increase the expression of stemness markers like CD44, Oct-3/4, Nanog, and drug resistance-associated molecules or anti-apoptotic proteins [93,94,95,96].