ERK2 knockdown in THP-1 macrophages blocks LPS-induced G-CSF expression.

<p>THP-1 cells were infected with lentivirus carrying specific shRNA for ERK1 or ERK2 and induced to differentiate by incubation with PMA (160 nM) for 3 days; lentivirus carrying luciferase shRNA (Luc) was used as a control, then the following tests were performed. (<b>A</b>) Levels of ERK1/2 and β-actin in the cells were determined by Western blotting; the data shown are typical of the results of three experiments. (<b>B</b>) Cells were treated with LPS (100 ng/ml) for 8 h, then G-CSF levels in the medium were determined by ELISA; untreated Luc cells were used as the control. (<b>C</b> and <b>D</b>) Levels of G-CSF mRNA (<b>C</b>) and TNF-α mRNA (<b>D</b>) in cells were determined by RT-qPCR, normalized to the levels of GAPDH mRNA, and expressed relative to levels in the Luc control (relative value = 1). In (B-D), the results are the mean ± SD for five independent experiments. *<i>p</i><0.05 compared to the corresponding cells not treated with LPS.