Fig. 1.

Schematic of cell fusion assay. Cells are transfected with cDNA plasmids encoding either T7-RNA polymerase (driven by a cytomeglavirus promoter) or yellow fluorescent protein (YFP) driven by a T7-promoter. Transfected cells are mixed in a 1:1 ratio and fusogen is added. At various times, fused cells are monitored by fluorescence microscopy, or analyzed by FACS to quantify the number of fused cells or to isolate fused cells