E84 staining does not block the proliferation of labeled cells. (A) Growth curves of E84-labeled 293T cells. Cells (5 × 10⁵) were incubated in 10 nM E84 solution (or PBS control) for 30 minutes. After labeling, cells were washed with medium and cultured for 4 days. Cell viability was measured every day using the CellTiter-Glo Luminescent Cell Viability Assay Protocol (Promega). (B) MFI of E84-stained cells in culture was measured by FACS daily. After day 3, E84 staining was not detected. Representative results from 3 independent experiments are presented.