FIGURE 4.

B[a]P-N⁶-dA blocks hRNAPII elongation. For each DNA template studied, four separate reactions were carried out as indicated above each lane in the gel: lane M, New England Biolabs 50-bp DNA ladder labeled with [³²P]phosphate; lanes 1–4, results for transcription using the unmodified DNA template illustrated in Fig. 1; lanes 5–8, transcription results using the DNA template modified with a B[a]P-N⁶-dA adduct, also illustrated in Fig. 1; lanes 9–12, results using the control DNA template containing a CMV immediate early promoter supplied with the HeLa nuclear extract. The components for each transcription reaction are indicated above the lanes.