A team of scientists have recently identified one of the molecules responsible for the tubular shape of blood vessels. Originally known for regulating blood vessel development for life, the vascular endothelial growth factor (VEGF) proteins analyzed by the research team have proven to be more interesting than initially thought. The team found that a certain variation of VEGF attracts an “instructor” protein. When this variant, with the instructor protein attached, docks with a receptor on the surface of a cell, a signal telling the cell to form a tube-like shape with its neighbours is sent to it. When the instructor cell is absent, the cells line up next to one another to form a sheet. Scientists believe that not only could this contribution allow blood vessels to be created from stem cells, but the discovery might be employed in other tube-like structures in the body, such as the lungs and the intestines. Far from being confined to blood vessels, the discovery thus opens the door to resolving the problem of three-dimensional reconstruction of organs from stem cells.