Tumor incidence and transgene expression. (A) Kaplan-Meier plot showing the percentage of tumor-free animals as a function of post-natal age in weeks for line 17 TG and WT females.(B) Top, tumor transgene expression (RT-PCR using Trizol-isolated RNA). Data is shown for two tumors and spleen of one lymphomatous TG female (M, markers). The relatively low -RT signal is due to contaminating DNA as demonstrated by loss of the signal after DNAse I treatment (last two lanes). Bottom, transgene expression in a tumor from another TG female, using RNA isolated with the less stringent Purescript protocol. The strong -RT signal is lost upon DNAse I treatment.