Cell adhesion is a basic process in cell biology, controlling cell growth, death, differentiation, movement, and tissue organization in normal cells, as well as the proliferation and metastasis of tumor cells. My laboratory focuses on the molecular basis for cell adhesion and migration. In particular, we are interested in the structures and functions of heterodimers in the INTEGRIN family. For example, we are studying mechanisms whereby integrin functions are rapidly turned on and off, and different integrins link to distinct cellular signaling pathways. In addition, we study other cell surface transmembrane proteins that associate with integrins. Remarkably, we have recently learned that transmembrane linker proteins, called tetraspanin proteins, allow the membrane proximal extracellular domains of integrins to play key roles in the recruitment of intracellular signaling enzymes such as protein kinase C, and phosphatidylinositol 4-kinase. Also we study how certain integrins may be linked to regulation of matrix metalloproteinase (MMP) production, a key process during cell and tissue remodeling and tumor cell metastasis. Most recently, we have deleted the tetraspanin CD151 gene from mice, and we are using those mice to investigate the role of CD151 during tumor progression.