(A) Murine C2C12 myoblasts were treated with RvD1 (100 nM) at onset of myogenic differentiation. At 3 days postdifferentiation, myotubes were fixed in 4% paraformaldehyde (PFA) and stained for sarcomeric myosin. Cell nuclei were counterstained with DAPI. Quantitative analysis was performed on 6 nonconsecutive fields of view per well to determine overall cell density (DAPI⁺ nuclei/mm²), the extent of myogenic differentiation (% DAPI⁺ nuclei within myosin⁺ cells), and mean myotube (multinucleated cell) diameter. (B) Confluent C2C12 myoblasts were induced to differentiate in the presence of RvD1 (0.1–1 μM), or NSAIDs, including NS-398 (50 μM), ibuprofen (500 μM), and indomethacin (200 μM). (C) C2C12 myotubes at day 3 postdifferentiation were pretreated with RvD1 (100 nM) for 30 minutes before stimulation with lipopolysaccharide (LPS, 100 ng/mL) for 3 hours in the continued presence of RvD1. mRNA expression of cytokines, including IL-6, MCP-1, and TNF-α, was determined by RT-PCR. (D) C2C12 myotubes at day 3 postdifferentiation were pretreated with RvD1 (100 nM) for 30 minutes and then stimulated with LPS (100 ng/mL) for 24 hours in the continued presence of RvD1. Conditioned culture medium was collected from the cells and analyzed for concentrations of the cytokines IL-6, MCP-1, and TNF-α by ELISA. (E) Confluent C2C12 myoblasts were induced to differentiate in the presence of exogenous TNF-α (20 ng/mL), with or without RvD1 (100 nM) cotreatment. At day 3 postdifferentiation, myotubes were fixed, stained, and quantified as described in A. Scale bars: 400 μm. Bars show the mean ± SEM of 3–8 replicates per group with dot representing data for a single independent culture well. P values were determined by 2-tailed unpaired t tests (A) or 1-way ANOVA followed by pairwise Holm-Šidák post hoc tests (B–E).