a, Confocal images of cultured PECs treated with siRNA–GeRPs (red/green). PECs were stained for F4/80 (blue) and nuclei (n) (Hoescht; blue). Arrows indicate GeRPs. b, Map4k4 mRNA expression from PECs treated with increasing Map4k4 siRNA concentrations. a.u., arbitrary units. c, Map4k4 and Tnf mRNA expression from PECs treated with PBS, unloaded GeRPs or scrambled (Scr) GeRPs. d, Tnf mRNA expression from PECs treated with Scr- or Map4k4-siRNA-containing GeRPs, ±6 h LPS (1 µg ml−1). e, Tnf-α secretion from PECs treated with Scr or Map4k4 GeRPs. Statistical significance was determined by ANOVA and Tukey post test. *P < 0.05. Results are mean ± s.e.m. f, PCR amplification of 5′ RACE products produces a band (arrow) reflecting the predicted RNAi-mediated mRNA cleavage product in Map4k4- but not Scr-siRNA-treated PECs.