Updated project metadata. Cell-to-cell communication plays a cardinal role in the biology of multicellular organisms. H2O2 is an important cell-to-cell signaling molecule involved in the response of mammalian cells to wounding and other stimuli. We previously identified a signaling pathway that transmits wound-induced H2O2 cell-to-cell signals within minutes over long distances, measured in centimeters, in a monolayer of cardiomyocyte cells. Here we report that this long-distance H2O2 signaling pathway is accompanied by enhanced accumulation of cytosolic H2O2 and altered redox state in cells along its path. In addition, we show that it requires the production of superoxide, as well as the function of gap junctions, and that it is accompanied by significant changes in the abundance of hundreds of proteins in different cells along its path. Our findings highlight the existence of a unique rapid long-distance H2O2-dependent signaling pathway that could play an important role in different inflammatory responses, wound responses/healing, cardiovascular disease, and/or other diseases