We aim to decipher the molecular and cellular mechanisms of tumor plasticity. We seek to understand how tumor cells change their differentiation state, and take advantage of this process to generate tumor heterogeneity and a constant pool of cancer stem cells/cancer propagating cells. We also seek to understand the role of the tumor microenvironment in this process, and elucidate the cross-talk between tumor cells a their neighbor cells. We believe that understanding these mechanisms and interactions will facilitate the development of novel strategies to attack this aggressive type of cancer.