The TPH1 protein was analyzed by western blot in extracts of these cells and was significantly elevated not only in MDA-MB-231 and T47D, but also in MCF7 cells, demonstrating that 5-HT biosynthetic capacity was increased in all breast cancer cell lines tested, with the highest level of expression occurring in MDA-MB-231 cells (Figure 1B). This evidence concerns the gene TPH1 and breast cancer.