NANOG and cancer: Breast CSCs enrichment is rapidly lost during in vitro culture because of incompatible with the tumor microenvironment in vivo.7 Recently, several new human CSCs models were established to identify compounds that can selectively target CSCs.8, 9, 10 Nanog is a core transcription factor firstly discovered in embryonic stem cells (ESCs) with essential functions in maintenance of self‐renewal and pluripotency of ESCs.11, 12 In recent years, the relationship between Nanog and cancer has received increased attention.