Thus, altogether our findings indicate that diffuse YAP1 expression is a consistent feature of SMARCA4-UT, explaining how previous erroneous annotation of both SMARCA4-UT cell lines and YAP1-positive NSCLC lines as SCLC, led to the grouping of these lines within a distinct YAP1-positive SCLC subgroup. Here, SMARCA4 is linked to small cell lung carcinoma.