Kinetics of HIV-Tat–induced expression of adhesion molecules on EC. EC monolayers were treated with 100 ng/mL HIV-Tat for different times at 37°C. The cells were harvested at indicated times, fixed in 2% paraformaldehyde, and washed with cold PBS. Cells were then resuspended in FACS binding buffer, and the expression of adhesion molecules was determined by flow cytometry as described in the Materials and Methods.