MT-CO1 and melanoma: Copper can more broadly affect the phenotype of melanoma cells, as it regulates the activity of proteins that are relevant and crucial for melanoma cells, including mitochondrially encoded cytochrome c oxidase subunit 1/2 (MT-CO1/2), lysyl oxidases, tyrosinase (TYR), mitogen-activated protein kinase 1/2 (MEK1/2), and Unc-51-like autophagy activating kinase 1/2 (ULK1/2) [27,37].