GRP and small cell lung carcinoma: However, based on the expression of several neuroendocrine (NE) markers, such as chromogranin A (CHGA), synaptophysin (SYP), neural cell adhesion molecule 1 (NCAM1/CD56) and gastrin-releasing peptide (GRP) SCLC can be classified into neuroendocrine-high (NE-high) or neuroendocrine-low (NE-low) tumor.