SYP and large cell neuroendocrine carcinoma: Consistent with our protein expression analyses, data from the public datasets [24, 27] confirmed “lineage ambiguities”: In both tuft cell-like SCLC and LCNEC, KRT5 mRNA expression levels were significantly higher (Fig. 3A), while expression levels of specific neuroendocrine markers (CHGA, SYP, and INSM1), and DLL3, a Notch ligand with therapeutic relevance in SCLC [29], were significantly lower than in their non-tuft cell counterparts (Fig. 3B, C).