Effect of β-arrestin 2 knockdown on the ability of capsaicin and endomorphin-2 to affect the lateral mobility of MOR and TRPV1 in the plasma membrane of HMY-1/TRPV1 cells. The diffusion coefficients (A,C) and the mobile fractions (B,D) of TRPV1 (upper panel) and MOR (lower panel) were obtained from FRAP measurements. The knockdown of β-arrestin 2 (β-Arr2(↓)) was performed 24 h before addition of the ligands. The cells plated in a glass bottom chamber were treated with capsaicin (Caps, 0.5 µM) or endomorphin-2 (End-2, 1 µM) for 5 min before measurements. FRAP experiments were performed on the bottom cell membrane using a Zeiss LSM 880 confocal microscope. The data were collected from three independent experiments, at least 50 cells in each group. Results are expressed as means ± S.E.M. Asterisks or hashes denote significant differences between control (Ctrl) or untreated (-) β-Arr2(↓) cells and different drug treatment groups (* p < 0.05, ** p < 0.01, *** p < 0.001 compared to corresponding control; #
p < 0.05, ###
p < 0.001 compared to corresponding β-Arr2(↓) (-)).