New cell line development for high antibody-producing mammalian cells. (A) Schematic diagram for the split GFP-based cell screening method. (B) Confocal microscopic images of cells transfected with a GFP-overexpressing vector (pEGFP-C1) or bicistronic vector having GFP fragements and both antibody chains (pNGFP-Light and pCGFP-Heavy). After transfection with these vectors, the cells were cultivated for two days at 30°C. DAPI was used for nucleus staining. Antibody titer was quantified from culture supernatant by ELISA.