FIGURE 4.

The ERK pathway is required for TGFβ stimulation of TGFβ1 promoter activity, which can be inhibited by km23-1 depletion. A, the ERK pathway is required for TGFβ stimulation of TGFβ1 promoter activity. Mv1Lu cells were transfected with phTG5-Luc. 24 h after transfection, the cells were pretreated with the MEK inhibitor PD98059 at the concentrations indicated for 30 min and then incubated in the absence or presence of TGFβ1 for an additional 24 h. The cells were harvested, and luciferase assays were performed as described under “Materials and Methods.” B, blockade of km23-1 partially inhibits TGFβ activation of ERK in HaCaT cells. HaCaT cells were transiently transfected with NC, km23-1, or km23-2 siRNAs and were treated with TGFβ1 (5 ng/ml) for the indicated times. Western blotting was performed using the indicated Abs. C, km23-1 and km23-2 siRNAs selectively and specifically knockdown endogenous km23-1 and km23-2, respectively. The efficiency of km23-1 and km23-2 knockdown was confirmed by real time RT-PCR. The data are representative of three independent experiments.