Consistent with the lack of involvement of p38α and p38β in regulation of stemness, treatment of NSCLC cells with SB203580, a compound that mainly inhibits p38α and p38β but only weakly p38γ and p38δ, modestly increased the expression of SOX2 but not that of Oct4 and other stemness proteins (Supplementary Figure 7A), and failed to increase the percentage of the side population or the ability to form spheres (Supplementary Figure 7B, 7C). This evidence concerns the gene POU5F1 and non-small cell lung carcinoma.