CDC of Y-443 against MDA-MB-231 cells. MDA-MB-231 cells and Daudi cells were incubated with Y-443 or rituximab together with human serum complement for 60 min at 37°C. The damaged cells were stained with propidium iodide. Antibody-specific CDC was calculated as described in Methods. The results are the mean ± S.D. of triplicate assays.