Many impediments of current anti-cancer therapies have urged scientists to discover new agents. As a result of growing spectrums of new targets and strategies and recent biological and biotechnological progresses, many anti-cancer agents such as monoclonal antibodies, small molecule tyrosine kinase inhibitors, and epi-genetic drugs have reached clinical trials. This review helps to understand the rationale for the development of inhibitors against major targets such as cell growth, proliferation, survival, and angiogenesis and recent targets such as the proteasome, heat shock proteins, and...