Figure 6

Volcano plots. (A): Volcano plot corresponding to the Taqman quantitative PCR. Black points in both upper corners correspond to differentially expressed genes (log2 fold-change higher than 1 and p-value lower than 10-6); (B): Volcano plot of the GE Healthcare data with the Edwards background correction method and a log2 transformation. A high number of false negatives (red points) are produced because of poor estimations of p-values; (C): Volcano plot of the GE Healthcare data with the Edwards background correction method and a glog transformation. The glog transformation compresses the fold-changes and produces a high number of false negatives; (D): Volcano plot of the GE Healthcare data with the Edwards background correction method and a hybrid transformation. Fold-changes and p-values are estimated using the log2 and the glog-transformations, respectively.