FIG. 4.

A novel form of Keap1 with retarded mobility is induced by tBHQ in a dose-dependent manner and requires C151. (A) COS1 cells transfected with expression vectors for either wild-type (WT) (lanes 1 and 2) or the indicated mutant Keap1 proteins (lanes 3 to 12) were treated with DMSO (−) or 25 μM tBHQ (+) for 16 h. Cell lysates were collected, electrophoresed through an SDS-7.5% polyacrylamide gel and subjected to immunoblot analysis with an antibody against Keap1. The arrows on the left side of the figure indicate the location of Keap1 and of a tBHQ-induced form of Keap1 that migrates with retarded mobility through an SDS-polyacrylamide gel. The positions of molecular mass markers are indicated on the right side of the figure. (B) Transfections into COS1 cells and subsequent immunoblot analysis were performed as described for panel A, except that transfected cells were treated with the indicated doses of tBHQ.