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. Author manuscript; available in PMC: 2013 Aug 9.
Published in final edited form as: Nat Rev Cancer. 2011 Feb;11(2):96–110. doi: 10.1038/nrc2998

Figure 1. DNA damage tolerance and carcinogenesis.

Figure 1

A) Replication forks can be blocked by lesions in DNA. When a translesion DNA synthesis (TLS) polymerase is available, a lesion can be bypassed by TLS, potentially causing point mutagenesis, or template switching can mediate bypass in an error-free manner (see Figure 2 for details). Point mutagenesis can lead to cancer formation in normal cells, or to resistance to therapeutic agents in cancer cells. B) In the complete absence of a TLS polymerase, no translesion bypass occurs (although there will still be some template switching) and replication forks collapse, leading to double-strand breaks and chromosome instability, which increases the incidence of cancer.