The quantitative real-time PCR results showed that the mRNA levels of FZD-1, p21, GLP-1, GINS1, and Notch2 were significantly increased with rescue of YB-1 expression in YB-1 knockout breast cancer stem cells and melanoma stem cells (Fig. 3d), suggesting that the transcription factor YB-1 was responsible for the expression of these five genes. This evidence concerns the gene YBX1 and breast carcinoma.