c-Src activation is required for AC-induced inhibition of DCs. MerTK^+/+ BMDCs (A) or sDCs (B) were incubated with the c-Src inhibitors E804 (10 nM) or PP1 (20 nM) for 1 hour and cocultured with ACs for 3 hours or left untreated, and stimulated with LPS (50 ng/mL). Nuclear NF-κB or SP-1 DNA-binding activity was determined via EMSA, and IκBα and β actin protein measured by Western blot. (C-D) MerTK^+/+ BMDCs were transfected with c-Src–specific or scrambled control siRNA, cocultured with ACs for 3 hours or left untreated, and stimulated with LPS (50 ng/mL for 0.5 hours or 1 μg/mL for 24 hours for IL-12 detection), and nuclear NF-κB and SP-1 DNA-binding activity and IκBα or β actin protein were examined (C), and IL-12p70 secretion was measured (D); *P < 10⁻³, DCs treated with c-Src–specific siRNA versus mock-transfected DCs or DCs transfected with control siRNA (Student t test). Data are representative of a minimum of 3 experiments. Error bars in panel D indicate ± SEM.