Here, the DNA-RNA hybrids synthesized in Stage 1 are converted into full-length double-stranded cDNAs. The primers for synthesis of second-strand cDNA are created by RNase H, which introduces nicks into the RNA moiety of the cDNA-mRNA hybrids. E. coli DNA polymerase I extends the newly created 3'-hydroxyl termini, using the first-strand cDNA as a template.
