Chemokine-induced internalization of CCR5. Internalization of CCR5 in the presence of various chemokines was estimated by FACS analysis of CHO-K1 cells expressing CCR5, using the 2D7 MoAb. The cells were incubated for 2 hours with the chemokines (500 nmol/L) before the test. The data (mean fluorescence) were normalized for the fluorescence of untransfected CHO-K1 cells (0%) and maximal fluorescence in the absence of chemokines (100%), and the displayed results represent the mean of three independent experiments (error bars: S.E.M.).