NMBR and small cell lung carcinoma: In the case of SCLC, GRPR (gastrin-releasing peptide receptor) [20, 21] and NMBR (neuromedin B receptor) [22] contribute to growth; cholecystokinin-1 (CCK1) and -2 (CCK2) [23] mediate growth and survival; and CXCR4 [24] induces growth and metastasis.