FIG. 4.

Representative inhibition experiment gel and graphical analysis. Serial dilutions of the inhibitor (DNT2300 hexaphenylguanide) were incubated with CXCR4-expressing cells. The fluorescent, photoactive derivative of T140 was added, followed by irradiation at 365 nm to induce cross-linking between the peptide and receptor. Samples were dissolved in SDS, run on an SDS-PAGE gel, and imaged with a fluorescent gel reader. The concentration of inhibitor is marked at the top of each lane. The intensities of the fluorescent CXCR4 bands (doublet indicated by arrow) were quantified and plotted with Sigma Plot to determine an approximate IC₅₀ (∼1 μM). A Western blot of the gel incubated with monoclonal antibody 1D4 was used to confirm the identity of the CXCR4 bands and their uniformity across the gel (not shown).