Fig 2.

Mouse transferrin receptor 1 is the entry receptor for MMTV. Human 293T cells were transfected with the mouse TfR2 (A), mouse TfR1 (B), or human TfR1 (C) cDNAs under the control of the CMV promoter and then infected with MMTV pseudotypes containing the lacZ reporter gene. After staining for lacZ, extracts were prepared from the cells and subjected to Western blot analysis with anti-TfR1 antibodies. Endogenous hTfR1 levels are below detection in this analysis. The polyclonal anti-TFR1 antibodies do not recognize TfR2.