a, Immunoblot of extracts from L929 cells stably expressing Firefly Luciferase-driven by an interferon sensitive response element depleted of STING by siRNA or expressing control siRNA. b, L929 cells, control or STING depleted as in a, were treated with various concentrations of STING agonist cyclic GMP-AMP (cGAMP), and Luciferase activity was read after 16 h. c, MDM were infected with HIV-1 wild-type (WT) or mutant HIV-1 CA N74D or HIV-1 CA(P90A) for 18 h (MOI of 2), total cell extracts were isolated and were heat and benzonase treated and were applied to L929 cells as in a and Luciferase activity measured at 16 h (Mean of 4 ± s.e.m. of biological replicates). d, As c except RNA was extracted from the cell extracts and were transfected into 293T cells to measure IFN-β promoter driven Luciferase activity after 16 h. Sendai virus infection served as positive control for immuno-stimulatory RNA (Mean ± s.e.m. of biological replicates). c, * represents statistically significant difference between data sets (P < 0.05, t-test), NS represents non-significant differences.