ASCL1 and small cell lung carcinoma: We report that TTF‐1 and achaete‐scute homolog 1 (ASCL1, also known as ASH1, an E‐box binding basic helix–loop–helix transcription factor, and a lineage‐survival oncogene of SCLC) are coexpressed and bound to adjacent sites on target genes expressed in SCLC, and cooperatively regulate transcription.