Monocarboxylate transporter 4 (MCT4), whose expression is also proportionally influenced by GLUT5 expression in CCA cells, plays a crucial role in transporting the accumulated lactate into the extracellular environment (Suwannakul et al. 2022; de la Cruz-López et al. 2019). The gene discussed is SLC2A5; the disease is cholangiocarcinoma.