KLC1 (kinesin light chain 1) functions as a regulatory component of the kinesin-1 motor protein complex, facilitating microtubule-based intracellular transport. The protein plays a crucial role in coupling cargo to kinesin heavy chains and modulating ATPase activity during organelle transport 1. KLC1 undergoes alternative splicing regulation by CELF1, with variant E (KLC1_vE) being particularly significant in disease pathogenesis 2. In pancreatic beta-cells, KLC1 mediates glucose-stimulated insulin granule movement along microtubules, though phosphorylation at Ser517/Ser520 does not appear to regulate this function 3. The gene shows clinical relevance across multiple diseases. In Alzheimer's disease, reduced CELF1 expression leads to increased KLC1_vE levels, promoting pathogenesis 2. KLC1 is associated with schizophrenia risk through rare coding variants, particularly damaging missense variants 4. Additionally, KLC1 serves as a fusion partner in various cancers, including KLC1-ROS1 fusions in pediatric glioma that activate JAK-STAT pathways 5 and KLC1-ALK fusions in lung cancer and mesenchymal neoplasms 67. Elevated KLC1 expression correlates with poor prognosis and increased lung cancer risk through epigenetic regulation 8.