A possible model of the processing of an embedded ribonucleotide and ribonucleotide-induced mutagenesis. 8-Oxo-rG could be generated by the incorporation of oxidized ribonucleoside triphosphates into DNA or by the oxidation of the embedded ribonucleotides. RNase H2 and BER cannot remove 8-oxo-rG21,22. NER is involved in the excision of such a damaged ribonucleotide. Alternatively, Pol η can bypass 8-oxo-rG to suppress the mutagenic events induced by the embedded ribonucleotide. The unrepaired ribonucleotide is subject to Top1-mediated processing, leading to the deleterious mutations.