IL-6Rα and IGF-I receptor formed a complex on plasma membranes of NOP2. (A) IP-Western analysis showed IL-6–dependent coprecipitation of IL-6Rα and IGF-I receptor β in NOP2 but not in ILKM3. (B) Confocal laser microscopy showed the colocalization of IL-6Rα labeled with PE (red) and IGF-I receptor labeled with FITC (green) in NOP2 but not in ILKM3. Colocalization is shown in yellow in the merged pictures. (C) Some IL-6Rα and IGF-I receptors were located at lipid rafts in NOP2. IL-6Rα or IGF-I receptor was recognized by specific antibodies labeled with PE (red), while lipid rafts were indicated in green with FITC-conjugated cholera toxin B subunits (CTXB). Fluorescent imaging at an initial magnification of × 630.