SOX2 and carcinoma: Research over the past few years characterizes SOX2 as (1) a transcriptional regulator of stemness in early embryogenesis and in ontologically more advanced, mostly neuro-ectodermal stem/progenitor cells, (2) a devastating oncogene in germ line-derived tumors, neuronal cancers and various carcinomas, and (3) a critical co-inductor in the reprogramming of terminally differentiated somatic cells to iPSCs.