Problem: The term "plasticity" has been used when describing several different concepts in cancer biology and development of cancer therapeutics. This term has been used in describing the concept of cancer stem cells, in the context of epigenetic alterations, and also applies to thinking about how cancer cell metabolism or interaction of cancer cells with immune cells changes over time. Describe what "plasticity" means using at least two examples from the course. Include in your answer how this complicates the identification of potential targets for cancer therapy and the evaluation of the effectiveness of these targets.