The SuperScript® IV First-Strand Synthesis System for RT-PCR is optimized for synthesis of first-strand cDNA from purified poly(A)+ or total RNA. The kit includes SuperScript® IV Reverse Transcriptase (RT), a proprietary MMLV mutant that produces robust and reliable cDNA synthesis in RT reactions. The SuperScript® IV synthesis system is significantly improved over the SuperScript® III-based system in inhibitor resistance, processivity, and reaction speed, while retaining all the benefits of the previous system, including increased thermostability, highly efficient full-length cDNA synthesis, and reduced RNase activity. The SuperScript® IV system is designed to provide reliable, consistent, and fast cDNA synthesis in the presence of inhibitors found in a wide variety of samples that cause other currently available RTs to perform inefficiently. The SuperScript® IV First-Strand Synthesis System contains all components needed for RT reactions, plus an additional control gene and primers, and provides the flexibility to customize the RT set-up to fit the needs of your application.