FIGURE 2.

IL-1R1 signaling initiates from lipid rafts. MCF-7 cells were treated with IL-1β for varying periods of time (0, 2.5, 5, 10, and 20 min). Lipid rafts were then isolated from the cells using a sodium carbonate density gradient method. Following centrifugation, the gradients were collected into 15 fractions. A, shown are the results from Bradford protein quantification of the fractions from an experimental series of lipid raft isolations. Lipid rafts were typically contained within the small protein peak found in fractions 5–7. B–F, Western blotting was performed to examine the signaling components in the isolated lipid raft-containing fractions. The antigen detected in each blot is indicated at the top of each panel.