POU5F1 and breast cancer: Consistently, elevated expression of Oct4 and Nanog has been reported in cancer cell lines and/or primary cancers from melanoma [19], [20], germ cell tumors [21], [22], [23], [24], [25] and cancers of the breast [24], [26], [27], prostate [28], lung [29], colorectum [30] and endometrium [31], and correlates with increased malignancy and acquisition of CSC properties.