Figure 5.

sFRP-2 and sFRP-3 bind to Drosophila Wingless when they are expressed as GPI-anchored cell-surface proteins. 293 cells were transiently transfected either with sFRP-2 (A and B) or with sFRP-3 (C and D) expression constructs in which the sFRP open reading frames were linked at their carboxy termini to a myc epitope-tagged GPI anchor sequence. The cells were incubated with conditioned medium containing Wingless protein, immunostained with affinity purified anti-Wingless antibodies, and examined by confocal microscopy. (A and C) Immunofluorescent staining. (B and D) Phase contrast.