TfRscFv facilitated liposome-mediated gene transfection of JSQ-3 tumor cells in vitro. Transfection efficiency was assessed by the β-galactosidase enzymatic assay and is given as mU β-galactosidase/mg protein (15,16). The attachment of TfRscFv significantly increased the transfection efficiency of cationic liposomes, (2- to 2.4-fold) as compared to non-targeted LipA. The gene transfection efficiency of TfRscFv-LipA1 (prepared by the lipid-film solubilization method) or TfRscFv-LipA2 (prepared by the direct anchoring method) is comparable to that of the human transferrin targeting lipoplex (Tf-LipA). TfRscFv-LipA2 showed slightly higher transfection efficiency than TfRscFv-LipA1, correlating with their immunoreactivities in the ELISA results in Fig. 2.