Source data for Figure S3D right: Experimental quantitative data on ligand-independent endocytosis (_obs) and standard deviations (stdCol_). Used in conjunction with the auxiliary model (Figure S4A and S4B). See 'Materials and Methods - Endocytosis assays' for details. time SAv_extracellular_obs stdCol-SAv_extracellular_obs SAv_cellsurface_obs stdCol-SAv_cellsurface_obs SAv_intracellular_obs stdCol-SAv_intracellular_obs min pM pM pM pM pM pM 0 999.27 0.33 NaN NaN NaN NaN 10 997.60 0.09 1.47 0.11 0.34 0.07 20 996.38 0.19 2.15 0.25 0.96 0.11 60 992.90 0.64 3.57 0.40 2.98 0.30