The main focus of the laboratory is the study of the tumor microenvironment (tumor-host interaction). In recent years we have learned that the tumor microenvironment plays an important role promoting tumor progression. Tumor angiogenesis and bone marrow-derived and inflammatory cells recruited at tumor sites have emerged as critical determinant of tumor progression. Many molecular mediators and regulators of angiogenesis and stromal event have been in largely elucidated in recent years. Our understanding of the functional relationship between the tumor microenvironment and tumor cells, is still limited. This is becoming particularly relevant in view of the potential targeting of stromal event to inhibit tumor progression. In this perspective it is now important to identify novel effective and safe target molecules, understand how tumors adapt to changes in the microenvironment induced by therapeutic interventions, and how current therapies may be improved and novel ones developed.