PPP6C depletion enhances 5′ppp dsRNA- and dsDNA-induced but not poly(I:C)-induced innate immune responses. (A) EA.hy926 cells were transfected with control nonspecific (NS) or PPP6C siRNA for 72 h and then transfected with poly(I:C) (0.5 μg/ml), 5′ppp dsRNA (4 μg/ml), dsDNA (4 μg/ml), or cGAMP (4 μg/ml) for 16 h. IFN-β production in the supernatant was measured by ELISA. (B to D) EA.hy926 cells were transfected with NS or PPP6C siRNA for 72 h and then transfected with 5′ppp dsRNA (B), dsDNA (C), or poly(I:C) (D) for the indicated time periods. IFN-β production in the supernatant was measured by ELISA. (E to G) EA.hy926 cells were transfected with NS or PPP6C siRNA for 72 h and then transfected with 5′ppp dsRNA (E), dsDNA (F), or poly(I:C) (G) for the indicated times. Cell lysates were immunoblotted with the indicated antibodies. The data shown are representative of three independent experiments. Data in panels A to D are presented as mean + SD. *, P < 0.05 by Student's t test.