Tat tethered to the EC surface promotes Namalwa cell adhesion. Namalwa cells were allowed to adhere to naive or Tat-coated living (A,B,D) or fixed (C) GM7373 EC monolayers in the presence of heparin (73 nM), of GRGDSPK or GRADSPK peptides (10 μΜ), or after a wash with PBS/NaCl. (D) GM7373 EC monolayers were left untreated or treated with heparinase III (10 mU/mL), washed, further incubated with GST-Tat or s-Tat (550 nM), and assayed for their capacity to promote SYN-NC adhesion. Each point is the mean ± SEM of 4 to 7 duplicate determinations. (B) Microphotographs of SYN-NCs adherent to naive (−Tat) or Tat-coated (+Tat) GM7373 EC monolayer.