Moloney Murine Leukemia Virus (M-MuLV, MMLV) Reverse Transcriptase is an RNA-directed DNA polymerase. This enzyme can synthesize a complementary DNA strand initiating from a primer using either RNA (cDNA synthesis) or single-stranded DNA as a template. (1-4). M-MuLV Reverse Transcriptase lacks 3´ → 5´ exonuclease activity.