Integrins are the major membrane proteins providing physical cell-matrix linkage and transmitting cellular force. Such force functions as both mechanical drive and regulative signal in various critical cellular functions including cell adhesion, migration and contraction. However, the tension transmitted by integrin molecules (termed as integrin tension), as the fundamental mechanical signal in integrin signaling, has been difficult to visualize and characterize, resulting in the poor understanding of its role in many cellular functions. This presentation will demonstrate innovative molecular tension tools developed in our lab. With these tools, we measure, map and manipulate integrin tension in live cells with piconewton (pN) sensitivity and submicron resolution. Our studies revealed the mechanical and regulative role of integrin tension in cell adhesion, cell migration and platelet contraction.