NOTCH1 and small cell lung carcinoma: Various other genes frequently altered in small-cell lung cancer (SCLC) include RBL1 and RBL2 from the retinoblastoma family, NF1B and PTEN tumor suppressors, NOTCH1, NOTCH2, NOTCH3, and NOTCH4 from the Notch signaling pathway, as well as ARID1, CREBBP, EP300, KMT2D, and SMARC4 that involved in regulating chromatin integrity.