Effect of NAA or NADMA on [3H]azidopine photoaffinity labeling of Pgp. DMSO control with CCRF-CEM Pgp only (lane 1) and CCRF-CEM/VBL100 Pgp only as controls (lanes 2 and 8); CCRF-CEM/VBL100 Pgp with 0.1, 1, 10, 100, and 200 μM of NAA (lanes 3–7), and with 0.1, 1, 10, 100, and 200 μM of NADMA (lanes 9–13) are shown.