FIGURE 2.

In vivo and in vitro growth rate of HeLa cells with tetracycline-inducible CAGE. A and B, stable tetracycline-inducible CAGE transfectant clones (10⁶ cells) were inoculated subcutaneously into athymic nude mouse. Following inoculation 10 mice were divided into two groups, with one group devoid of treatment and the other group administered doxycycline (dox) (1 μg/ml). At the onset of tumor formation, tumor diameter was measured every other day with calipers (A). At 35 days after inoculation, the mice were euthanized, and tumor weight was measured (B). Values are the means ± S.D. of tumors from five mice. CAGE abundance in representative primary tumors (P) from each mouse was assessed by immunoblotting with an antibody to CAGE (inset in B). C, tetracycline-inducible CAGE transfectant clones were seeded at a low density and cultured in the absence or presence of doxycycline (1 μg/ml), and cell numbers were counted directly every 24 h over the course of 6 days. For delayed overexpression of CAGE, doxycycline was added to the culture medium of untreated cells 3 days after initial seeding of the cells (arrows above Δ+dox). *, p < 0.01 versus −dox at day 6 in culture.