Bacterial components stimulate increased RIG-I protein expression in human microglia. Human microglial (a) and astrocytic (b) cell lines were stimulated with the bacterial components flagellin (FLG, 10–100 ng/ml), Pam3Cys (Pam, 10–100 ng/ml), and lipopolysaccharide (LPS, 1–10 ng/ml) for 18 h. In addition, hμglia human microglial cells were transfected for 4 h with 0.1 μg/ml BDNA, 1 μg/ml 5′pppRNA, 0.5 μg/ml bacterial genomic DNA (gDNA) (c) or 1 μg/ml bacterial RNA (d) and cell lysates were collected 24 h post transfection. Cell lysates were analyzed for protein expression of RIG-I and the housekeeping gene, β-actin, via immunoblot analysis. Relative RIG-I protein expression normalized to β-actin is displayed graphically below the representative immunoblot. Data are expressed as mean ± SEM for a minimum of three independent experiments. Asterisks denote statistical significance compared to unchallenged cells as determined by Student’s t test (p < 0.05).