Activation of MAPK and NF-κB pathways by HNE-modified Col II in human OA chondrocytes. Cellular extracts from incubated chondrocytes (see legend 1) were subjected to assess total and phospho-p38 MAPK, ERK1 (p44), ERK2 (p42) and NF-κB-p65 by (a) Western blot analysis using specific antibodies or by (b) ELISA procedure using commercial kit. (b1) p38 MAPK, (b2) ERK1, (b3) ERK2, (b4) NF-κB-p65. ANOVA tests and Bonferroni's multiple comparison were performed to compare each condition. The data are means ± SEM of n = 4. *P < 0.05, **P < 0.01, ***P < 0.001.