POU5F1 and neoplasm: As shown in Fig. 6B, at 10 days post-transplantation, a significant proportion of cells expressing OCT4, SOX2 or MYC were detected in L1475luc-rtTA-OSKM tumor sections (Oct4+ 7.701 ± 2.727%; Sox2+ 3.108 ± 2.191%; c-Myc+ 24.96 ± 2.662%) relative to control L1475luc-rtTA tumor sections (Oct4+ 0.648 ± 0.149%, p = 0.011; Sox2+ 0.189 ± 0.193%, p = 0.08; c-Myc+ 14.15 ± 4.972%, p = 0.029, relative to OSKM-expressing cells), where the levels of reprogramming factors remained essentially undetectable (Fig. 6C).