Figure 6.

Fatty acids do not block TPA- or EGF-induced phosphorylation of Erks or p38 kinase and JNK kinase activity. JB6 Cl 41 cells were treated and Western blot analysis was carried out as described in Materials and Methods. (A and B) Erks and p38 kinase were phosphorylated after treatment with either TPA or EGF. None of the fatty acids were capable of blocking the phosphorylation. p-Erk and p-p38 indicate the phosphorylated proteins. (C and D) JNK activity was assessed by determining the phosphorylation of JNK's direct substrate, c-Jun. Western blotting was carried out by using a specific c-Jun antibody against c-Jun phosphorylated at serine-63. Both TPA and EGF induced an increase in JNK activity, and none of the fatty acids blocked the increase.