NANOG and neoplasm: PEO1-derived tumor spheroids appear also acquiring a typical CSC-like and an EMT-like phenotype characterized by a significant overexpression of Oct4, Nanog, and Sox2 stemness marker genes and a strong upregulation of the mesenchymal marker Vimentin (Vim) and its transcription factors Snail and Slug and a parallel breakdown of the epithelial marker e-cadherin (E-cad).