Research into treatments for breast cancer relies more and more on an understanding of how the cells of tumor tissue act when they are exposed to a new or different drug. To find these new or different drugs to treat cancer, researchers are looking at proteins that help cancer cells grow, such as a group of proteins called Kinases. This is important because many of the newest cancer drugs are designed to block kinases causing the cancer cells to die and the tumors to shrink. However, blocking only one of the kinases at a time is often less effective than the investigators expected because when you block one kinase another can take its place. For this reason, the investigators may need to treat breast cancer with more than one kinase-blocking drug at a time. However, the investigators don't yet know what the best combination of drugs should be, because it is hard to measure all the possible kinases. Previous studies have only been able to identify less than 10% of the hundreds of kinases in cancer cells.