RvD1 promotes the IL-4-induced alternative activation of BV-2 cells. BV-2 cells were treated with vehicle (0.038% ethanol) or different concentrations of RvD1 (1 nM, 10 nM and 100 nM) for 30 minutes in the absence or presence of Boc-2 (10 μM), and then stimulated by IL-4 (10 ng/ml) for 24 hours. (A, B) The expression of Arg1 and Ym1 proteins was assessed by Western blot. A representative result from three independent experiments is shown. Quantification for Arg1 and Ym1 was normalized by β-actin. Data are presented as mean ± SEM for three independent experiments. Asterisks indicate statistically significant difference (*P < 0.05, **P < 0.01). (C, D) Representative images of BV-2 cells with positive immunofluorescence staining for Arg1 (C) and Ym1 (D). Scale bars indicate 20 μm.