Anybody know of published studies assessing the contribution to expression variability of the various parts of the GeneChip expression data production process - RNA isolation, labeled target preparation, Hybe+wash+scan+analysis? There are two related reports on the Affy web site comparing GeneChip output - focusing on presents calls, and comparisons of absolute expression of genes of unknown true expression level: 1. An Analysis of Blood Processing Methods to Prepare Samples for GeneChipŽ Expression Profiling 2. Globin Reduction Protocol: A Method for Processing Whole Blood RNA Samples for Improved Array Results Are there other published studies on this topic (doesn't have to be blood - any source of RNA that can be treated with alternative RNA isolation protocols would present the same problem of deciding which protocol is best for a given application)? Thanks in advance. -Francois [[alternative HTML version deleted]]