MB (Myoglobin) is a 154-amino acid protein (~17kDa), is a member of the globin superfamily and expression of myoglobin is highest in skeletal and cardiac muscle. Functionally, myoglobin is well accepted as an O2-storage protein in muscle, capable of releasing O2 during periods of hypoxia or anoxia. Myoglobin is also thought to buffer intracellular O2 concentration when muscle activity increases and to facilitate intracellular O2 diffusion by providing a parallel path that augments simple diffusion of dissolved O2. Furthermore, myoglobin is used together with cTnI or cTnT in clinical practise for better specificity in AMI diagnosis.