CXCR4 and small cell lung carcinoma: We observed a marked downregulation of SCLC-specific gene clusters (CXCR4, RRM2, FOXM1, CCNB2, CEP55, PLK1, AURKA, AURKB, and CCNB1) in SBC5 cells overexpressing miR-1 (Fig. 5A).