FIG. 2.

Heterogeneous response of promoter activity to topoisomerase inhibition. (A) Nuclear run-ons of Raji cells. (B) Nuclear run-ons of Raji cells with pMYC/CAT. c-myc exon 2 (slot 10) and CAT (slot 9) distinguish between the c-myc RNAs encoded by the endogenous c-myc gene and the hybrid MYC/CAT mRNA encoded by the episome pMYC/CAT. The arrow indicates the direction of transcription. Cpt, camptothecin; Adr, adriamycin; TSA, trichostatin A. The cells were incubated with inhibitors for 4 h. A 10-min run-on reaction was performed.