NANOG and breast cancer: In addition to these target genes, NOTCH1 activation stimulates expression of embryonic stem (ES) cell pluripotency transcription factor Nanog. The Nanog-Oct4-Sox2 (NOS) transcription factors activate self-renewal and inhibit differentiation in human and mouse ES cells and the NOS signature is enriched in claudin-low and basal-like breast cancer subtypes [62-64].