NOTCH1 and small cell lung carcinoma: Moreover, we found substantial intratumor heterogeneity of NOTCH1-ICD expression, ranging from 1% and 80% of tumor cells (Figure 9B), consistent with data from a prior IHC study of NOTCH1 in SCLC (52) and the known intratumor heterogeneity of Notch signaling in SCLC mouse models (24).