FIGURE 6.

B[c]Ph-N⁶-dA interferes with transcription elongation in all cells lacking NER or TCR, whereas B[a]P-N⁶-dA only exhibits an effect when NER is compromised. A, normal primary human fibroblasts; B, XPA^−/− primary human fibroblasts; C, XPC^−/− primary human fibroblasts; D, CSB^−/− primary human fibroblasts. Time courses for each cell type: unmodified control vector (▴); vector modified with B[a]P-N⁶-dA (■); vector modified with B[c]Ph-N⁶-dA (●). RFP mRNA levels were normalized as the percentage of the maximum average RFP mRNA level compared with that of the control vector in a given cell type.