MSTN and cancer: Some myokines (such as interleukin-6, tumor necrosis factor- alpha) have environment-dependent functions and can exhibit pro-cancer or anti-cancer effects depending on the microenvironment; while factors such as myostatin show stable anti-tumor potential by regulating key molecular pathways such as the PI3K/AKT pathway, epithelial-mesenchymal transition, and HIF-1α.