Throughout the previous century, a big effort to understand the biochemical basis of cancer was made. One of the principal branches of cancer research used drugs to prevent the formation of new blood vessels – a process called angiogenesis – responsible for nutrient supply to the tumour. These drugs are generally called antiangiogenics. It was discovered that some types of tumour have or develop resistance to these drugs. Therefore, mechanisms of resistance, aggressiveness, invasion and/or metastasis after treatment are nowadays relevant areas of study. Recently, a protein that could be involved in increased invasiveness of tumour cells after antiangiogenic treatment appeared. This project presents some evidence that indicates that this protein, CD44, might play a role in increased invasion after antiangiogenic treatment in mouse models of renal carcinoma.