The Monocarboxylate Transporter (MCT) family is a group of transmembrane proteins responsible for the transport of monocarboxylates such as lactate and ketone bodies into and out of cells. The main family members include MCT1 to MCT4, which consist of multiple transmembrane domains and are mainly located in the cell membrane. The MCT family is involved in regulating energy metabolism, pH balance, and cell signaling by facilitating the transmembrane transport of monocarboxylates, affecting cell growth and survival. The expression of MCT family members is tissue- and cell-specific, and mutations or dysregulation of their genes are associated with various diseases, including cancer, cardiovascular diseases, and metabolic disorders.