Cell storage and thawing. (A) The scheme shows manipulations of PBMC before RNA extraction. Where appropriate, RNA was preserved in both RNAlater and TRIzol. (B) The effect of freeze-thawing PBMC, combined with the effect of storage in various RNA-preserving reagents, on RNA quality is shown. RNA samples were analyzed on StdSense gels to assess integrity expressed as RNA quality index (RQI). (C) For the same conditions, PCR signals in cDNA that was synthesized from the RNA samples were determined. R, RNAlater; T, TRIzol. *P < .05.