PIEZO1 and Atrophy: Given that the Ca2+ chelator EGTA, as well as inhibitors of CaMKK and Piezo1, upregulated the expression of atrophy-related genes in nonstimulated cultured muscle cells, we hypothesized that a decrease in [Ca2+]i to a level below the basal concentration is a trigger for the development of immobilization-induced muscle atrophy.