Figure 4.

Effect of DNA damage and PARP inhibition in vivo. Total RNA was extracted from HeLa S3 cells treated with MNNG (150 μM), 3AB (5 mM), or MNNG together with 3AB. ³²P-labeled cDNA was synthesized from mRNA transcripts by reverse transcription, using oligo(dT) as a primer. The resulting cDNA molecules were then fractionated on an ethidium bromide/agarose gel (1% agarose), and labeled cDNAs were visualized by autoradiography. As a positive control, mRNA extracted from nontreated HeLa S3 cells (MNNG, 0 min) was exposed to 150 μM MNNG in vitro for 30 min and reverse-transcribed (lane M).