Table 1.

Quantitative analysis of endogenous and transgenic K-Ras4b RNA in nontransgenic and bitransgenic mice treated with doxycycline for the times indicated

	K-Ras4b G12D	Endogenous K-Ras4b
Nontransgenic	<0.00001	1.0
Bitransgenic, No Dox	0.000045*	1.1
Bitransgenic, 9d Dox	0.02	0.56
Bitransgenic, 2m Dox	1.1	0.41
Bitransgenic, On 2m Off 3d	0.00016*	0.54

Total RNA was prepared from the right accessory lobe and used for quantitative Taq-Man™ RT–PCR as described in Materials and Methods. Each sample was amplified for endogenous K-Ras4b, transgenic K-ras4b^G12D, and GAPDH. After amplification, data was plotted and, for each individual sample, amplification curves for both endogenous and transgenic K-Ras message was standardized to GAPDH. We arbitrarily designated the level of K-Ras4b in nontransgenic mice equal to 1. We then compared the GAPDH-standardized levels of endogenous and transgenic K-Ras message to the level of endogenous K-Ras seen in the nontransgenic sample. The amplification curves indicated that the mutant and endogenous K-Ras RNAs were amplified with nearly identical efficiencies (data not shown). Standard deviations determined after multiple assays were in the range of 5% to 20% excepting the two low abundance samples (indicated with an asterisk) where the signal was near background and the standard deviation was about 50%.