POU5F1 and cancer: Recently, we contributed to the understanding of the role of an acidic TME in cancer cell stemness demonstrating that exposure to low extracellular pH induces the expression of pluripotency markers such as Nanog, KLF4, OCT4 and Sox2 and the over-expression of stemness markers such as CD133, CD243 and ALDH1A1 in melanoma cells [14].