Indeed, paclitaxel treatment of MCF7 cells for 7 days resulted in an increase in the so called “side population” of cells that exclude the dye Hoechst 33342 (Figure 3A) and results in a ten-fold increase in the CD44+CD24low population of SKBR3 (Figure 3B) and MCF7 breast cancer cells (Figure S5A). This evidence concerns the gene CD44 and breast cancer.