qRT-PCR and Western blot analyses confirmed that SCLC CM treatment and POSTN-expression induced the activation of NOTCH1 signaling in LX-2 cells, as evidenced by the upregulation of NOTCH1, HES1/5, DLL1/4, and JAG2 (Fig. 4F-G and S4A-B). This evidence concerns the gene DLL1 and small cell lung carcinoma.