To revert the differentiated cancer cells into cancer stem cells, constructs expressing YB-1, SOX2, POU3F2, OCT-4, OLIG1, SALL2, and Bmi-1 were separately transfected into YB-1 knockout melanoma stem cells or breast cancer stem cells to express these proteins (Fig. 5b). This evidence concerns the gene YBX1 and breast cancer.