The inhibition of WNT transcription and activation of NOTCH are features of undifferentiated human embryonal carcinoma and ES cells [37], and may be mediated by the SFRP1 gene, which is repressed in differentiating NT2/D1 cells (derived from human EC cells) after treatment with retinoic acid [38]. Here, SFRP1 is linked to embryonal carcinoma.