PDE2A and small cell lung carcinoma: Consistent with the correlation between NEUROD1 and the miR-139-5p in the SCLC cell line (Fig. 4C), PDE2A expression was concordantly observed in NEUROD1-positive SCLC cases, and PDE2A staining was absent or showed weak positivity in NEUROD1-negative SCLC-A cases (Fig. 5D).