Figure 4

Validation of cancer vs stromal RNA ratio using the expression of pair-wise human and mouse homologous housekeeping genes measured by species-specific probes. The log2 expression ratio between human SSPs and mouse SSPs were plotted in three cases using the initial experimental data, when probes were exposed to: A) only human RNAs, B) only mouse RNA, and C) both human and mouse RNA. Consistent with the results shown in Figure 3, the expression ratios were larger than 10 (log2(10)=3.3, the dashed blue lines) when SSPs were exposed to the indented RNA only, while the 75th quantile of expression ratios were between 0 and 10 when exposed to equally human and mouse RNAs (panel C).