Figure 1.

Induction of Bak by UVB and abrogation of the Bak pathway by E6 proteins. (A) Human primary keratinocytes, HT1080 cells and human p53-null keratinocytes (RTS3b line) were treated with UVB (15 mJ/cm²) and the cells harvested at 0–43 h (only human primary keratinocytes survived after 24 h). Equal protein samples were resolved by SDS-PAGE, with Bak, p53 and α-tubulin levels detected by Western blotting using monoclonal antibodies. (B) HT1080 E6 polyclonal cell lines were treated with UVB (15 mJ/cm²) and the cells harvested 24 h later. Proteins were detected as in A. The membrane was exposed to X-ray film for 1 min prior to development. (C) Polymorphic forms of p53 from B were resolved on a 10% PAG and detected as previously. (D) HT1080 E6 cells were treated with 60 μg/mL cycloheximide 5 min post UV treatment (15 mJ/cm²). Protein extracts were prepared at the indicated time points following cycloheximide treatment and Bak levels determined by Western blotting. The membrane was exposed to X-ray film for 20 min prior to development to detect low levels of Bak.