FIG. 4.

(A) Semiquantitative RT-PCR analysis of RNA samples obtained from villus enterocytes from control or T-antigen-expressing mice. Adh was used as a loading control. (B) Steady-state levels of E2F proteins in transgenic intestines. Protein extracts from whole intestines were used to analyze the levels of E2F2 and E2F3a by immunoblotting; β-tubulin was included as a loading control. E2F1 levels were very low and were detected reproducibly only in nuclear extracts; histone H3 was used as a loading control. Lanes labeled (+) and (−) refer, respectively, to normal and KO MEFs used as controls. Levels of the activators E2F2 and E2F3a are higher in intestinal villi expressing TAg^wt or TAg^N136 than in control or TAg³²¹³-expressing intestinal villi.