RNA yield and RIN values. RNA yield and RIN values for the five different RNA extraction protocols. (A) RNA yield (in μg) obtained after one or (if required) two DNase treatments from 500 μl blood using four different protocols/ kits for RNA extraction from whole blood as well as the LeukoLOCK™ filter system. (B) RIN values of the RNA extracted from blood samples preserved in different buffers. Please note that samples collected with the RNA filter “Leuko” were stored in RNAlater® just as the whole blood samples “RNAlater”. The RIN values of both collection methods differ dramatically and represent both the upper and lower limit of the performance of all tested preservation buffers.