The effect of Bip, HSP70 and ERp57 on receptor dimerization. HEK293 cells were transfected with WT AT1R-v1/v2 and β2AR-v1/v2. After 48 hours, cells were harvested, washed with 1X PBS and resuspended in 100 μl PBS. Fluorescence was then measured using an EnVision plate reader at 528 nm. Results are expressed as means ± sem of at least 3 experiments. * = p < 0.05; ** = p < 0.01 compared with negative controls using two-tailed paired Student's t test. Results are representative of 3 independent experiments.