Fig. 3. Expression patterns of the fluorescently tagged proteins. Confocal images (top) and confocal images merged with transmitted-light images (bottom). (I) HEK-293T cells transiently transfected with GFP-tagged hFGR3 (R3-GFP) together with Myc-tagged SOCS1 (S1-Myc) (C) or empty vector (A,B). (II) HEK-293T cells transiently transfected with CFP-tagged SOCS1 (S1-CFP) together with R3-GFP (F) or empty vector (D,E). After 8 hours in serum-free medium, cells treated with or without 50 ng/ml FGF and 5 µg/ml heparin for 1 hour. (III) HEK-293T cells transiently transfected with S1-CFP together with PRLR (G). After 8 hours in serum-free medium, cells were treated with ovine prolactin (PRL) for 1 hour. (IV) RCS WT and RCS S1 cells were pulsed with [³⁵S]methionine for 30 minutes and treated with 20 ng/ml FGF and 5 µg/ml heparin. In the indicated periods of time, cells were lysed and subjected to immunoprecipitation with anti-hFGFR3 antibodies. Immunoprecipitated proteins were separated on 10% SDS-PAGE followed by fluorography. Bars, 10 µm.