RNA sample (degradation factor 21) degraded after purification, RNA was isolated directly after PBMC isolation. In parallel, whole cell extracts from the same cells were prepared as a source for endogenous RNases by freezing cells which had been diluted 1:1 in distilled water with 5 % (v/v) glycerol. After thawing, cell debris was spun down in a tabletop centrifuge and supernatants were used as cell extracts. 30 ug of purified RNA were incubated with 50 ng of these cell extracts in a volume of 100 ul for 10 minutes at room temperature in the presence of 50 mM Tris.HCl pH 8.3, 75 mM KCl, 3 mM MgCl2 and 10 mM DTT. After this incubation, RNA was again purified by Trizol. Targets were produced using standard Affymetrix procedures from about 8ug of total RNA. Keywords = Homo sapiens, RNA degradation, microarray
