Case-matched ratios-race group tests. Figure 4 depicts a Volcano plot on the left and a Modified MA plot on the right. The volcano plot shows the presence of genes (represented by dots) that have high gene expression profile changes and that are also highly statistically significant as evidenced by the p-values and the large fold change values (genes of interest fall above the dashed bold line). On the volcano plot, the x-axis denotes fold change of the Caucasian samples (i.e., a minus 2 represents a negative 2.0 fold change of tumor vs. normal) and the y axis denotes fold change of the African American samples. The modified MA plot shows fold change on the axis and intensity on the x-axis. The dots in the dashed squares in the upper left hand corner of the MA plot contains genes whose fold change values met our filtering criteria of positive in CA and negative in AA. The lower right dashed square contains genes that met our filtering criteria of positive in AA and negative in CA.