Effects of SOCS1 on MAP kinase signaling. SW1353 cells were transfected with SOCS1 or shSOCS1 vectors to overexpress or inhibit SOCS1, as described in Methods. A representative immunoblot image showed that SOCS1 overexpression decreased phosphorylation of p38 and JNK, whereas SOCS1 knockdown increased their phosphorylation in the presence of IL-1β (10 ng/ml, A). The relative proportions of phosphorylated to total protein were determined with densitometry by using Image J software (version 1.48c, ; B). Data were expressed as the means ± SEM (n = 3). OE, overexpression; KD, knockdown.