NCS1 (Neuronal Calcium Sensor 1) is a calcium-binding protein that serves as a key regulator of calcium-dependent signaling pathways in neurons and other cell types. The protein functions as a neuronal calcium sensor that modulates G protein-coupled receptor phosphorylation in a calcium-dependent manner and can substitute for calmodulin 1. NCS1 directly interacts with inositol 1,4,5-trisphosphate receptors (InsP3R1) through residues 66-110 on the suppressor domain, enhancing channel open probability and increasing intracellular calcium signaling 1. The protein also regulates phosphatidylinositol-4-kinase-B (PI4KB) activity through direct interactions, controlling PI(4)P synthesis essential for membrane remodeling processes including mitophagy and inflammation responses 2. In pathological contexts, NCS1 demonstrates significant clinical relevance across multiple diseases. The protein is overexpressed in various cancers including liver hepatocellular carcinoma, breast cancer, and melanoma, where it correlates with poor prognosis and immune infiltration patterns 3. In lung adenocarcinoma, NCS1 functions downstream of DLX1 transcription factor and upstream of c-MYC, forming a critical oncogenic axis 4. Additionally, Mendelian randomization studies have identified NCS1 as potentially involved in multiple sclerosis pathogenesis, particularly affecting blood-brain barrier integrity and oligodendrocyte function 5. These findings establish NCS1 as both a fundamental calcium signaling regulator and a clinically significant biomarker across neurological and oncological contexts.