The samples are centrifugated at 5000 rpm in an tabletop centrifuge.

After the spin (10’ at 3,000 rpm), the supernatants are precipitated in RNase-free centrifuge tube by adding 1/10 volume 3 M NaAcetate (pH 5.3) and 2.5 volumes of cold ETOH 100% overnight at -20°C. Centrifugation (30’ at 12000 rpm).