This analysis was successful in 10 of 22 samples, all of which demonstrated a high degree of mutual exclusivity in the cellular expression of ASCL1 and NEUROD1 (Fig. 1f), with the median proportions of dual-positive cells being 4.5% (range, 2.1%–6.8%) for SCLC-A tumors co-expressing NEUROD1 and 5.0% (range, 3.7%–5.7%) for SCLC-N tumors co-expressing ASCL1. This evidence concerns the gene NEUROD1 and small cell lung carcinoma.