P11（Cat No.:R065583）, also known as S100A10, is a member of the S100 family of calcium-binding proteins and functions as a key regulator of serotonin signaling and neuronal plasticity. It forms a complex with annexin A2 and influences membrane trafficking and ion channel regulation. P11 is strongly implicated in mood regulation and has been found to be downregulated in depressive disorders. It is widely used in neuroscience and psychiatric research to study the molecular mechanisms underlying depression and antidepressant response, serving as a potential biomarker and therapeutic target for mood-related disorders.