Last but not least, different natural and synthetic compounds, such as triphenylmetane gentian violet, lunasin, retinoic acid and chelerythrine chloride, have also been shown to specifically target the melanoma CSC subpopulation by regulating the expression/activity of the embryonic transcription factors Oct4, Sox2 and Nanog [345,346,347,348]. Here, POU5F1 is linked to melanoma.