Selenocysteine (SeC), a naturally occurring selenoamino acid, induces a caspase-independent apoptosis in MCF-7 breast carcinoma cells, accompanied by poly (ADP-ribose) polymerase (PARP) cleavage, caspase activation, DNA fragmentation, phosphatidylserine exposure, and nuclear condensation. This evidence concerns the gene PARP1 and breast carcinoma.