In addition to protein phosphorylation and dephosphorylation, protein degradation as well plays key role in regulating signal transduction pathways and cell proliferation. Please answer the give problems:

1) Please give one illustration to describe how protein degradation regulates signal transduction pathway;

2) Please give another illustration to describe how protein degradation influences cell proliferation.

3) Do you think targeting protein degradation procedure could be an efficient cancer therapeutic strategy? If your answer is YES, please describe which protein comprising protein degradation process could be a good drug target for cancer therapy and how to design the drug targeting it? If your answer is NO, please describe why.