The SLC16A1 gene encodes the Monocarboxylate Transporter 1 (MCT1) protein, a vital proton-coupled symporter that facilitates the rapid transmembrane movement of metabolic substrates, including lactate, pyruvate, and ketone bodies (acetoacetate and β-hydroxybutyrate). This gene is ubiquitously expressed across nearly all human tissues to maintain energy balance and pH homeostasis, with notably high levels labeled in the heart, oxidative skeletal muscle fibers, erythrocytes (red blood cells), and the brain (specifically in oligodendrocytes and the blood-brain barrier), while being uniquely "disallowed" or suppressed in normal pancreatic beta-cells to prevent inappropriate insulin release ^[1]. Functionally, MCT1 is central to the "lactate shuttle" mechanism, allowing tissues to coordinate metabolic fuel exchange by facilitating either the influx or efflux of substrates depending on the concentration gradient and proton motive force ^[2]. Mutations in SLC16A1 are clinically linked to Erythrocyte Lactate Transporter Defect, which causes exercise-induced muscle cramping and fatigue, and Monocarboxylate Transporter 1 Deficiency, a rare disorder characterized by recurrent episodes of severe ketoacidosis and vomiting triggered by fasting or infection ^[3]. Conversely, gain-of-function mutations in the gene's promoter lead to familial hyperinsulinemia type 7 (HHF7), where exercise triggers excessive insulin secretion, while its widespread overexpression in various cancers (such as melanoma and lung cancer) supports the Warburg effect by managing lactate efflux to prevent intracellular acidification and fueling tumor progression ^[4].

The B6-huSLC16A1 mouse is a humanized model constructed through gene-editing technology, in which the sequences from the ATG start codon to the TGA stop codon of the endogenous mouse Slc16a1 gene are replaced with the sequences from the ATG start codon to the TGA stop codon of the human SLC16A1 gene. This model can be used for research on diseases such as Erythrocyte Lactate Transporter Defect, Monocarboxylate Transporter 1 Deficiency, familial hyperinsulinemia type 7 (HHF7), and various cancers, as well as for screening, development, and preclinical evaluation of SLC16A1-targeted therapeutics.