SERPINI1 （Neuroserpin） is an inhibitory serpin which is expressed primarily in the central nervous system. Even though the physiological target of SERPINI1 is still vague， amassed evidence suggest that SERPINI1 has an imperative role in controlling proteolytic degradation of extracellular matrix （ECM） during synaptogenesis and the subsequent development of neuronal plasticity. The neuroprotective role of SERPINI1 has been demonstrated in transgenic mice lacking SERPINI1 expression. The deficiency of SERPINI1 in these mice is linked with motor neuron disease characterized by axonal degradation. In humans， defects in SERPINI1， caused by point mutations in the neuroserpin gene， trigger a hereditary disorder known as the familial encephalopathy with neuroserpin inclusion bodies （FENIB）.
