Exogenously expressed CD45RO- and CD45RB-EGFP translocated to lipid rafts in response to IL-6. (A) Lysates from U266 cells expressing EGFP-tagged CD45RO, CD45RB, or CD45RA at the carboxy terminus were subjected to immunoblotting using anti-CD45 Ab. ^* and ^** indicate endogenous CD45RO and CD45RB, respectively. (B) Cells were inoculated at 10⁴ cells/mL without (○) or with IL-6 (•) and counted at 0, 2, 4, and 6 days using the cell sorter. Values shown in these figures are the mean ± 1 SD. (C) Cells were subjected to sucrose density gradient ultracentrifugation followed by immunoblotting with the antibodies indicated. (D) Lipid rafts were cross-linked as in Figure 3B to clearly show the colocalization of CD45-EGFP and lipid rafts. The location of lipid rafts was visualized using TRITC-labeled CTB, and CD45 could be observed by EGFP fluorescence.