Fig. 2.

Effects of LPS pretreatment on the LPS-induced production of PGE₂ in RAW 264.7 cells. RAW 264.7 cells were pretreated with concentrations of LPS 50 pg/mL (SL-LPS) or LPS 50 ng/mL (L-LPS) with refresh complete media once a day for 3ds consequently and the cells were then cultured for 24 hr with refresh complete media in the presence or absence of LPS (1 μg/mL). These experiments were run in tetraplicate and repeated at least twice. Each value represents the mean ± SE. *p < 0.05 and **p < 0.01. Significantly different from the value in each control. ^#p < 0.05. Significantly different from the value in each SL-LPS.