Cells in the body are exposed to physiological and pathophysiological stimuli that encompass both chemical and mechanical factors. It is important to understand how these factors modulate functions at cellular and organ levels. Compared to the large amount of information on cellular or organ responses to chemical factors, there is a paucity of knowledge on the effects of mechanical factors. Recent advances of fluorescence proteins and microscopy make it a very useful tool for elucidating the mechanotransduction processes; the state-of-the-art technologies for live-cell imaging of signaling is particularly valuable for investigating the spatial and temporal aspects of molecular mechanisms in mechanobiology. This review will cover the basic knowledge of fluorescence proteins and their application for biological research. In particular, the development and characterization of biosensors based on fluorescent resonance energy transfer (FRET) will be discussed. Genetically encoded FRET biosensors, which allows the imaging and quantification of tempo-spatial activation of molecules, will be introduced to demonstrate how the initiation and transmission of biochemical signals in response to local mechanical stimulation can be visualized in live cells. Specific emphasis will be on the elucidation of molecule hierarchy of signaling transduction in live cells upon the mechanical stimulation.