Abstract Background: MiPEP133 is a microprotein encoded by the miR-34a precursor. In normal cells, it functions as a tumor suppressor and is expressed in colon, stomach, ovary, uterus, and pharynx, but its levels are markedly reduced in cancer. Localized in the mitochondria, miPEP133 regulates mitochondrial homeostasis through interactions with mitochondrial chaperones and has been reported to induce apoptosis and inhibit tumor cell migration in other cancer types. However, its functional role i