POU5F1 and lung cancer: Interestingly, the transcription factors OCT4, Nanog, BMI1, Notch1, ALDH1 and Sox2, known to be sufficient to reprogram mouse or human somatic cells to undifferentiated, pluripotent stem cells, were found to be significantly increased in hybrids compared to parental lung cancer cells, indicating their stemness phenotype (Figure 5B).