Lipid rafts are required for IL-6-induced proliferation and the CD45-Lyn pathway. U266 CD45⁺ cells starved of IL-6 for 12 hours were preincubated with or without 10 mM MCD for 30 minutes and then stimulated with IL-6 (10 ng/mL). (A) Cells cultured with or without IL-6 were collected after 24 hours, and live cells were enumerated with a cell sorter. Data are shown as a ratio compared with before stimulation. □ indicates control (no MCD); ▪, MCD. The data are expressed as the mean ± SD from 3 different experiments, and ^** indicates P < .01 compared with no MCD treatment. (B) Cells stimulated with IL-6 were recovered at 5, 10, and 30 minutes. Anti-P-Src family (Tyr⁴¹⁶) was used to detect active Src by immunoblotting. Immunoblotting of Lyn confirmed equal protein loading. (C) Cells pretreated with or without 10 mM MCD were stimulated with IL-6. After being fixed, cells were stained with FITC-conjugated CTB and anti-CD45 followed by rhodamine-conjugated anti-mouse IgG. Representative images obtained by LCM are shown.