Roads also cover streets, bridges, tunnels, supporting structures, junctions, crossings and interchanges. Some neurons also communicate via electrical synapses, which are direct, electrically conductive junctions between cells. The molecules responsible for creating cell junctions include various cell adhesion molecules. Axons transmit signals to other neurons by means of specialized junctions called synapses. Porous junctions called intercalated discs form junctions between the cells. Thus cardiomyocyte adherens junctions differ from epithelial adherens junctions and desmosomes. The gastrointestinal tract generates motility using smooth muscle subunits linked by gap junctions. Building works include construction of three road tunnels, five bridges and three junctions. Gap junctions electrically and chemically couple cells throughout the body of most animals. This causes endothelial hyperplasia, abnormal junctions, and diabetic retinopathy. An important component of the adherens junctions are the cadherin proteins. Farnborough is near junctions 4 and 4a of the M3 motorway. The area is close to junctions 3 and 4 of the M4 motorway. Alternate life paths branching out from each of those critical junctions are examined. Magnetoresistive RAM stores data in magnetic storage elements called magnetic tunnel junctions (MTJs).