1μg linearized DNA Transcription buffer (T3 or T7 RNA polymerase) 4 μl NTP DIG RNA (Boehringer) 2 μl RNAse inhibitor (35 units/μl) 1 μl T3/T7 RNA polymerase (20 units/μl, Stratagene) 1 μl Sterile water to 20 μl total