Figure 6.

A proposed mechanism leading to carcinogen-specific oncogene preferences. The schematic depicts carcinogen-induced damage to a relevant segment of the Braf gene centered on codon 636. Transcription-coupled repair removes potentially mutagenic DMBA adducts from the antisense strand (left), whereas mutagenic ENU adducts on the sense strand persist, culminating in ENU-induced Braf^GTG636GAG mutations. An inverse scenario is proposed to play out at Hras codon 61 (not shown), such that ENU adducts on the antisense strand are repaired, whereas mutagenic DMBA adducts on the sense strand persist, culminating in DMBA-induced Hras^CAA61CTA mutations.