Nicotinic acid adenine dinucleotide phosphate (NAADP) sodium salt is a potent second messenger in calcium signaling pathways. It mobilizes Ca²⁺ from intracellular acidic stores, such as lysosomes, by activating two-pore channels (TPCs). This compound is widely used in biochemical and cell biology research to investigate calcium-dependent processes, including exocytosis, fertilization, immune cell activation, and neuronal signaling. It also serves as a tool in pharmacology to study drug impacts on calcium homeostasis, oxidative stress, and related metabolic pathways.