Celecoxib enhances apoptosis of MDA-MB-231-E1A and MDA-MB-435-E1A stable transfectants. (a) Cell cycle distribution of MDA-MB-231-E1A and MDA-MB-435-E1A cells was detected by fluorescence-activated cell sorting after a 5-day exposure to 0 or 40 μM celecoxib. The percentage of cells in sub-G1 (apoptosis) appears at the upper right of each graph. (b) Western blots of MDA-MB-231 and MDA-MB-435 cells treated with 0 or 40 μM celecoxib for 5 days and tested for cleaved caspase-9 (cl-cas-9), uncleaved and cleaved caspase-8 (cl-cas-8), PARP (uncleaved and cleaved), E1A, and actin. Cleaved PARP and cleaved caspase-9 levels were higher after celecoxib treatment in the MDA-MB-231-E1A and MDA-MB-435-E1A stable transfectants, but expression of cleaved caspase-8 (cl-cas-8) did not change.