Figure 2
Cell uptake, retention and internalization assays for iso-[131I]SGMIB-VHH_1028 on HER2-positive BT474 breast carcinoma cells. (A) Total cell-bound activity and non-specific binding, measured by co-incubation with 100-fold excess of trastuzumab, after a 1 h incubation at 4 °C. (B) Retention of 131I activity after incubation at 37 °C for various times expressed as membrane-bound, internalized and total cell-associated activity; corrected for nonspecific binding by co-incubation with trastuzumab and (C) Internalization rate determined by plotting the ratio of internalized fraction over surface bound fraction, corrected for nonspecific binding, over time; internalization rate constant (ke) derived by linear regression (R2 = 0.8471). Surface-bound % activity and internalized % activity are presented as the percentages of initially cell-bound radioactivity after an initial incubation at 4 °C in these compartments. Surface-bound + internalized + supernatant = 100% at all time points.
