In addition, high expression of miR-1 in normal lung tissues and low expression of miR-1 in SCLC tissues was validated through in situ hybridization, whereas low expression of CXCR4, FOXM1, and RRM2 in normal lung tissues and high expression of CXCR4, FOXM1, and RRM2 was observed in commercially available human SCLC tissue microarray (supplementary Fig. S15). Here, RRM2 is linked to small cell lung carcinoma.