Our laboratory at the Center for Life Sciences is interested in understanding the heterotypic crosstalk that operates between the epithelial and the stromal compartments within carcinomas, with particular emphasis on how these interactions influence cancer metastasis. Our previous work indicated that certain bone-marrow-derived progenitor cells termed mesenchymal stem cells (MSCs) can home specifically to developing neoplasms where they integrate into the tumor stroma. Within this microenvironment, the tumor-associated MSCs become activated, and initiate de novo secretion of chemokines, cytokines, growth factors, and matrix proteins which act on the cancer cells and promote their growth, motility, invasion, and metastasis. The major current efforts of our group are now directed towards (1) deciphering the nature of the cancer-derived systemic signals that affect the bone marrow, and how such interactions mobilize MSCs and cause their recruitment to the tumor microenvironment; (2) characterizing the nature of the heterotypic interactions that cause the activation of MSCs within the tumor stroma, and (3) elucidating the various mechanisms by which MSCs exert their pro-malignant functions.