MTHFD2 and small cell lung carcinoma: Differential expression of genes-upstream miRNAs (RBMS3-hsa-miR-7–5p, NEDD9-hsa-miR-18a-5p, CRIM1-hsa-miR-18a-5p, TGFBR2-hsa-miR-9–5p, MYO1C-hsa-miR-9–5p, KLF4-hsa-miR-7–5p, EMP2-hsa-miR-1290, TMEM2-hsa-miR-18a-5p, CTGF-hsa-miR-18a-5p, TNFAIP3-hsa-miR-18a-5p, THBS1-hsa-miR-182–5p, KPNA2-hsa-miR-144–3p, GPR137C-hsa-miR-1–3p, GRIK3-hsa-miR-144–3p, and MTHFD2-hsa-miR-30a-3p) were identified in SCLC.