Fibronectin-carbon-nanotube (CNT) hybrid nanostructures are proposed as a platform to control the adhesion and growth of cells. The structure and role of extracellular matrix proteins, such as fibronectin, in the CNT-cell interactions are revealed by atomic force microscopy. The focal adhesion sites on fibronectin-carbon-nanotube hybrid nanostructures induce selective cell growth, including selective filopodial growth of human mesenchymal stem cells.