Effects of SOCS1 on NF-κB signaling. NF-κB p65 (Ser311 and Ser536) showed no alteration in phosphorylation after treatment with IL-1β (10 ng/ml) in SOCS1-overexpressing SW1353 cells, whereas SOCS1-knockdown cells increased levels of p65 phosphorylation at Ser311 (A). The level of IκB was increased by SOCS1 overexpression and decreased by SOCS1 knockdown (B). Accordingly, NF-κB-mediated luciferase activity was significantly reduced by SOCS1 overexpression after IL-1β treatment (C). Data were expressed as the mean ± SEM (n = 3). OE, overexpression; KD, knockdown; *P < 0.005 by Mann–Whitney test.