In contrast to other SCLC subtypes, these SMARCA4-deficient SCLC-Y tumors showed expression of RB1, weak cytokeratin staining and isolated expression of synaptophysin in the absence of other neuroendocrine markers INSM1 and CD56 (Fig. 3; Supplementary Fig. S3A). The gene discussed is SYP; the disease is small cell lung carcinoma.