MA139 cells expressing dCAT-1-g resembled FerrD2 in their susceptibility to virus infection ( Table 3 , Exp. 2 and Table 1 ) and sensitivity to F-S MLV-induced syncytia (Fig.  4B ). The cells with the unglycosylated receptor were, like FerrD2, efficiently infected by MoMLV. Syncytia were produced in these transfectants with the same viruses that are cytopathic in FerrD2, and no cytopathic response was observed with viruses that are also noncytopathic in FerrD2. Thus, the complete absence of N-glycans on dCAT-1 did not alter the ability of the dCAT-1 receptor to mediate virus induced syncytium formation in MA139 cells, nor did it alter the panel of viruses that were cytopathic and/or infectious in the transfectants.