Structure and expression of the double-labeled GFP plasmid system. (A) The pIS integrating sphGFP vector. (B) TheHPRT1-tpzGFP survival plasmid. P-CMV, P-TK, and P-RSV indicate the promoters of herpes TK1, CMV, and RSV, respectively. IVS represents the rabbit globin second intron. PA stands for polyadenylation signal. Solid arrows indicate open reading frames translated in the transduced human cells. (C–E) HIS4 cells expressing the pIS construct. (F–H) Clone 12 cells that express both the sphGFP from the pIS construct and tpzGFP from the episomal survival plasmid. PanelsC and F are photographs of the phase image. Fluorescent images in panels D,E,F, andG were obtained using filter sets that preferentially detect sphGFP (D,G) or tpzGFP (E,H). The Clone 12 cells were maintained in hygromycin B selection to retain the survival plasmid.
