POU5F1 and neoplasm: (1) This study demonstrates the novel finding of three CSC subpopulations within MDBMSCC, with; (2) one CSC subpopulation within the tumor nests, expressing EMA, CD44, SOX2, SALL4, OCT4, pSTAT3, and NANOG; (3) a second CSC subpopulation is within the stroma between the tumor nests, expressing SOX2, SALL4, OCT4, pSTAT3, and NANOG; and (4) a third CSC subpopulation expressing CD34, SOX2, SALL4, OCT4, pSTAT3, and NANOG localized to the endothelium of the microvessels within the stroma.