FIGURE 6.

Overexpression of Cbl-c and HSP27 enhances the ubiquitin-proteasomal degradation of Nox4 and inhibits senescence in lung fibroblasts. A and B, IMR-90 cells were transfected with Cbl-c or HSP27 and control (empty vector, EV) cDNA plasmids. After transfection, cells were serum-starved and treated without or with 100 nm bortezomib for 2 h. Cells were lysed, and immunoprecipitation (IP) was performed as described under “Experimental Procedures.” The levels of polyubiquitinated Nox4 and total protein levels of Cbl-c and HSP27 were determined by Western blotting. MW, molecular weight; Ub, ubiquitin. C and D, the levels of Cbl-c, Nox4, α-SMA, FN, p16, pRb, and GAPDH in total cell lysates of IMR-90 cells transfected with control (EV), Cbl-c, or HSP27 cDNA plasmids were determined by Western blotting. Representative results are shown.