We are now at an exciting era when our increased understanding of cancer biology jointly with the rapid advances in biotechnologies are allowing us to test fundamental concepts in cancer and ultimately translate them into the evolution of targeted cancer therapy. Resistance to cell death, especially to apoptosis, is an important feature of tumor cells, which is also described as one of the hallmarks in cancer. The research presented in this book supports the concept that apoptosis induction in tumor cells is a vital player in anticancer therapies. Although we already have a good knowledge of apoptosis machinery in cancer, various seemingly unrelated pathways (for example PAI-1 - uPA system) may also have linked to this important hallmark of cancer. Overall, a thorough understanding about cancer biology including taking tumor microenvironment into consideration is the foundation for the development of "targeted cancer therapy".