Application of the EAR normalization tool for the amplification of a specific blood mRNA ( IL8 ). (a) Amplification of blood IL8 mRNA relative to EAR mRNA and to the three most stably expressed housekeeping genes. Pearson's correlation r = 0.95; P < 0.0001. (b) Median blood IL8 mRNA levels versus EAR and versus the three most stable control genes in ten control participants. Samples from the National Neurological Institute-IRCCS "Carlo Besta", Milan (Italy).