Plasmid pLC119/pLC120 DNA substrates containing an OGG1 crosslink present on the template strand (left), or coding strand (right) of a transcriptional unit (construction described in Methods) were transfected into wild-type (V79, dark bars) and NER-deficient (V-H1, light bars) cells, and repair assays performed as described above. The graph depicts mean percent repair, ± SEM, N=3, *P < 0.05.