SLC44A5 encodes a choline transporter that facilitates choline transport across cell membranes with a Km value of approximately 12-50 µM, aligning with physiological plasma choline concentrations 1. Functionally, the protein regulates choline efflux from cells and modulates cell proliferation, with knockdown studies demonstrating reduced choline efflux and increased cell proliferation, while overexpression produces opposite effects 2. SLC44A5 is significantly upregulated in hepatocellular carcinoma tissues and non-invasive lung adenocarcinoma lesions 34. In hepatocellular carcinoma, SLC44A5 knockdown inhibits cell viability, induces G1 cell cycle arrest, promotes apoptosis, and suppresses invasion 3. The gene shows evidence of natural selection in British populations over 4,500 years, with significant changes in predicted expression levels 56. Clinically, SLC44A5 variants affect birth weight in cattle, with reduced expression associated with larger birth size due to enhanced cell proliferation 2. The transporter is sensitive to inhibition by hemicholinium-3, decynium-22, and verapamil 1. SLC44A5 represents a potential therapeutic target in cancer treatment and may serve as a neoantigen in immunotherapy approaches 37.