Figure 7.

Combination of LT-resistant MKK2 and MKK4 reverses LT-induced c-Jun reduction and cell growth arrest. A, sequence alignment of the docking sites of MKKs, including the three reported docking sites of MKK7. B, Hepa1c1c7 cells expressing GFP (control), LT-resistant MKK2 (MKK2CR), MKK4 with a replacement of the MKK7 D site (MKK7-4), or MKK2CR + MKK7-4 were treated with LT for 0, 2, and 4 h. The levels of c-Jun, p-JNK1/2, p-Erk1/2, and β-actin were determined by Western blotting. The intensities of protein bands were quantified using the Image Studio software of the Odyssey system and normalized by the amounts of β-actin; relative amounts are shown below each lane. C, proliferation of Hepa1c1c7 cells expressing GFP (control), LT-resistant MKK2, MKK4 with a replacement of the MKK7 D site, or MKK2CR + MKK7-4, which were treated with or without LT for 48 h. Shown are the cell proliferation inhibition percentages from three independent experiments. Open symbols represent three independent experiments; solid bars indicate the average, and the asterisk indicates a statistically significant difference.