Figure 2. Phosphorylation of ERK MAPK and its upstream targets were additively promoted by PA or mmLDL in LPS-stimulated macrophages. J774 cells were incubated with PA and then treated with or without LPS. Cell extracts were collected and phosphorylation of ERK was analyzed using immunoblotting (A). Macrophages were treated with LPS with or without mmLDL. Phosphorylation of ERK was analyzed as mentioned above (B). TLR4 and MyD88, the upstream molecules of ERK MAPK, were analyzed after treatment LPS with or without PA (C) or mmLDL (D). J774 cells were incubated with U0126, an ERK inhibitor, or DMSO and then treated with or without PA or mmLDL. The effect of U0126 on PA or mmLDL-induced elevation of IL-6 (E) and IL-1β (F) secretion was analyzed. Experiments were conducted with technical duplicates, and data presented are based on 3 independent replicates.

ANOVA = analysis of variance; DMSO = dimethyl sulfoxide; ERK = extracellular signal-regulated kinase; IL = interleukin; LPS = lipopolysaccharide; MAPK = mitogen-activated protein kinase; mmLDL = minimally modified low-density lipoprotein; NS = not significant; PA = palmitate; TLR = toll-like receptor.

^*p<0.05, ^†p<0.01.