POU5F1 and osteosarcoma: Interestingly, a study by La Noce et al. indicated that VPA could induce an increased expression of stem markers including CD133, OCT4, SOX2 and NANOG in osteosarcoma cell lines, and an increased ability in sarcospheres and colonies formation efficiency, suggesting that HDAC2 is a key factor regulating both cancer stem cells (CSCs) phenotype and in vivo cancer growth [50].