Figure 2

Constitutive L1 expression results in reduced retrotransposition potential. (A) Scheme for stable cell line generation. Wild-type cells were transfected with the desired expression vector. Selection was applied to assure the presence of this vector and the resulting cells were expanded under selection from colonies to a new cell line. (B) Constitutive L1 expression in HeLa cells results in lowered retrotransposition potential. Mobilization of a tagged L1 or a tagged Alu element, which confers neomycin resistance to a cell upon successful retrotransposition as described previously, was measured in HeLa cells selected to stably express various L1 proteins. Data are means and SD (error bars) of at least three independent measurements. Asterisks signify a significant (Student t-test, P ≤ 0.05) difference from retrotransposition levels seen in HeLa open reading frame (ORF)2 ER-- cells. (C) Constitutive L1 Expression in HCT 116 Cells results in lowered retrotransposition potential. The mobilization of a tagged L1 or a tagged Alu element, which confers neomycin resistance to a cell upon successful retrotransposition as described previously, was measured in HCT cells selected to express stably either L1 ORF2 or luciferase. T Data are means and SD (error bars) of at least three independent measurements. Asterisks signify a significant (Student t-test, P ≤ 0.005) difference from retrotransposition levels seen in HCT 116 luciferase cells.