Binding and antiproliferative effects of ANG4043 and anti-HER2 mAbs on tumor cells. Binding and antiproliferative effects of ANG4043 and anti-HER2 mAbs on tumor cells. A, confocal microscopy showing cellular localization of mAbs on BT-474 cells. After a 1-hour incubation of BT-474 cells with anti-HER2 or ANG4043 (1 μg/mL), confocal microscopy was performed to visualize localization of HER2 receptor and mAbs. Cell surface localization of HER2 receptor is shown in red (a, e) and native anti-HER2 (b) or ANG4043 (f) in green. Nuclei were Hoechst-stained blue (c, g). A merge of the three signals shows overlapping cell surface distribution between the antibodies and the HER2 receptor in yellow (d, h). Representative images from three experiments are shown. B, binding of mAbs to HER2-positive BT-474 breast cancer cells (n = 3 experiments performed in duplicate). C, antiproliferative effect of anti-HER2 and ANG4043 on HER2-positive BT-474 cells. D, antiproliferative effect of mAbs on HER2-positive SKBR3 cells. Antiproliferative evaluation on cancer cells was performed using [3H] thymidine incorporation assays two times in quadruplicate. Data represent the mean ± SD. Anthony Regina et al. Mol Cancer Ther 2015;14:129-140 ©2015 by American Association for Cancer Research