Polmyxin B partially protects LPS stimulated RAW 264.7 cells from CEES toxicity and blocks NO production. Panel A: Macrophages incubated with 50 ng/ml LPS or/and 500 μM CEES were simultaneously treated with or without 10 μg/mL polymyxin B (as indicated) for 18 hours. Cell viability was measured using the MTT assay (see Materials and Methods) and expressed as OD at 575 nm. Panel B: Macrophages were incubated as described above. NO production was measured as nitrite concentration in the culture media as described in Materials and Methods. Mean values not sharing a common letter are significantly different (p < 0.05).