Examples of interaction between "tissue type" and "sample storage". Error bar plots for least square means for differential gene expression data for (i) LPL (ii) APRT, (iii) C12 orf 139 and (iv) ZNF 800 genes. LPL shows the example with no interaction between "tissue type" and "sample storage", where as the other three genes show the examples of significant interaction - i.e., the differential expression in tumor tissue is significantly affected by the storage type. In each plot, breast tumor tissue is shown as blue square and adjacent normal breast tissue as red triangle; data from FF samples are presented on the left side and that of FFPE samples on the right side. The error bars represent standard error of mean.