Kinetics and concentration dependence of Gal-2– and Gal-4–induced PS exposure. (A) Desialylated HL60 cells (dsHL60) cells were incubated with 3 μM Gal-4 or 10 μM Gal-2 for the indicated times followed by detection of PS externalization. Control indicates the inclusion of PBS alone. (B) dsHL60 cells were incubated with Gal-2 or Gal-4 at each indicated concentration for 4 hours followed by detection for PS externalization. Results shown are the averages of duplicate analyses and are representative of at least 2 separate experiments. Error bars indicate the standard deviation of duplicate samples.