PMB in Hsp70-treated astrocytes behaves as PKC inhibitor rather than endotoxin inhibitor. A) Pretreatment of astrocytes only with the highest PMB concentration (10 μg/ml) caused significant reductions in the pro-inflammatory activity induced by the recombinant Hsp70, while the pro-inflammatory response of LPS-treated astrocytes was significantly reduced by the addition of 1 and 10 μg/ml of PMB. Primary astrocytes were treated with Hsp70 (5 μg/ml) containing 1.5 pg/ml of endotoxins or LPS (2.5 ng/ml) in the presence or absence of PMB (**P < 0.01, n = 6). Differential expression of cytokines and chemokines was assessed in primary astrocytes after 24 hours by using quantitative RT-PCR. B) The amounts of Tnf in culture media from astrocytes treated with Hsp70 (5 μg/ml) or LPS (2.5 ng/ml) in the presence or absence of PMB were measured by using ELISA (**P < 0.01, *P < 0.05, n = 6). C) The level of Tnf was significantly reduced in media from astrocyte cultures treated with Hsp70 in the presence or absence of PKC inhibitor (Gö6976, 10 nM and 100 nM). Culture media was collected 24 hours after treatment, and then the Tnf level was detected using the ELISA kit (**P < 0.01, n = 6). Hsp70, heat shock protein 70; LPS, lipopolysaccharides PKC, protein kinase C; PMB, polymyxin B.