DHX9 loss triggers dsRNA and dsDNA antiviral sensing pathways and IFN signaling in SCLC cells. A, Growth curves of the indicated SCLC cell lines (n = 3). B, Flow cytometry analysis of apoptotic (annexin V+) cells in Scramble and sgDHX9 H196 and H446 cells. Data are representative of three independent experiments (left). Quantification of apoptotic cells is shown (right; n = 3). C, Growth curves of the indicated normal cell lines (n = 3). D, Flow cytometry analysis of apoptotic (annexin V+) cells in Scramble and sgDHX9 FC1010 and RPE cells. Data are representative of three independent experiments (left). Quantification of apoptotic cells is shown (right; n = 3). E, qRT-PCR analysis of the immune-related genes comparing Scramble and sgSTING + sgMAVS H196 cells transfected with siCtrl or siDHX9 (n = 3). 36B4 was used as a reference. F, ELISA of human IFNβ protein in conditioned medium from Scramble and sgSTING + sgMAVS H196 cells, transfected with siCtrl or siDHX9 (n = 3). SM: sgSTING + sgMAVS. G, Immunoblot (IB) of the indicated proteins in Scramble and sgSTING + sgMAVS H196 cells transfected with siCtrl or siDHX9. H, Growth curves of Scramble and sgSTING + sgMAVS H196 cells, transfected with siCtrl or siDHX9 (n = 3). Data represent mean ± SEM. ns, not significant; *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001 by unpaired Student t test (A, B, C, and D), two-way ANOVA followed by Tukey multiple comparisons tests (E, F, and H).