Low-power laser irradiation (LPLI) leads to photochemical reaction and then activates intracellular several signaling
pathway. Reactive oxygen species (ROS) are considered to be the primary messengers produced by LPLI. Here, we
studied the signaling pathway mediated by ROS upon the stimulation of LPLI. Src tyrosine kinases are well-known
targets of ROS and can be activated by oxidative events. Using a Src reporter based on fluorescence resonance energy
transfer (FRET) technique, we visualized the dynamic Src activation in Hela cells immediately after LPLI. Moreover, Src
activity was enhanced by increasing the duration of LPLI. In addition, our results suggested that ROS were key
mediators of Src activation, as ROS scavenger, vitamin C decreased and exogenous H<sub>2</sub>O<sub>2</sub> increased the activity of Src.
Meanwhile, Gö6983 loading did not block the effect of LPLI. CCK-8 experiments proved that cell vitality was
prominently improved by LPLI with all the doses we applied in our experiments ranging from 3 to 25J/cm<sup>2</sup>. The results
indicated that LPLI/ROS/Src pathway may be involved in the LPLI biostimulation effects.