Galectins induce PS exposure in cell lines without accompanying apoptosis. Representative histograms of dsHL60 cells treated with PBS (A), 10 μM Gal-2 (B), or 20 μM camptothecin (C) for 18 hours followed by flow cytometric analysis for DNA degradation (TUNEL assay). Error bars represent the standard deviation of duplicate samples. The dsMOLT-4 or dsHL60 cells were treated with 5 μM Gal-4 (D), 10 μM Gal-2 (E), or 20 μM topoisomerase inhibitors (etoposide for MOLT-4 cells or camptothecin for HL60 cells) for 18 hours followed by flow cytometric analysis for DNA degradation (TUNEL assay). The dsMOLT-4 cells (F) or dsHL60 cells (G) were treated with either 3 μM Gal-4 or 20 μM topoisomerase inhibitors (etoposide for MOLT-4 cells or camptothecin for HL60) for the indicated times followed by the determination of viable cell number by trypan blue exclusion using a hemocytometer. Results shown are the averages of duplicate analyses and are representative of at least 2 separate experiments. Error bars represent the standard deviation of duplicate samples. Representative dot plots for dsHL60 cells treated with PBS (H), 10 μM Gal-2 (I), or 20 μM camptothecin (J) for 18 hours followed by flow cytometric analysis for changes in the light-scattering properties of the cells. Gate values of cells experiencing no changes in forward- and side-scatter profile are shown.