ERK signaling is required for some macrophage responses to M-CSF.

<p>(A) Wild-type bone marrow-derived macrophages were treated with 2 ng/ml M-CSF for the indicated times, lysed, and analyzed by Western blotting. Data represent two independent experiments. (B) Bone marrow-derived macrophages were pre-treated for 30 min with U0126 or DMSO vehicle (all others) and then treated with 2 ng/ml M-CSF for 10 min, lysed, and analyzed by Western blotting. Densitometric values (in arbitrary units) for LysM, E1 and ERK1/2 respectively were 33.7, 31.9 and 32.3 for β-actin; 43.7, 36.1 and 6.81 for ERK2; and 31.3, 54.9 and 14.0 for p-ERK2. Data represent two independent experiments. (C) and (D) Bone marrow-derived macrophages were pre-treated for 30 min with U0126 or DMSO and then treated with 2 ng/ml M-CSF for 24 h. RNA expression was measured by qRT-PCR. Each data point represents mean ± standard deviation of triplicate samples. Data are representative of three independent experiments. (E) Bone marrow macrophages were pre-treated with U0126 or DMSO, treated with 2 ng/ml M-CSF for 24 h, collected by detaching the cells using PBS with 10 mM EDTA, stained with 2 μg/ml anti-CD115, and analyzed by flow cytometry. Data represent two independent experiments. Labels: -, untreated; +, treated with M-CSF; B6, C57BL/6J; E1, <i>Erk1</i>^<i>-/-</i>; E2, <i>Erk2</i>^{<i>flox/flox</i>}<i>Lyz2</i>^{<i>Cre/Cre</i>}; U, U0126-treated C57BL/6J. **: <i>P</i><0.01, *: <i>P</i><0.05, NS: <i>P</i>>0.05.