LMP-1 antisense oligodeoxynucleotide treatment induces cleavage of PARP. Western blot analysis of PARP expression in the EBV-positive lymphoblastoid cell line, X50-7, was performed after exposure to unmodified oligodeoxynucleotide in serum-free medium with liposomes for 24 and 48 hours. Lanes 1 and 4, untreated controls; lanes 2 and 5, control oligodeoxynucleotide (SS1)-treated; lanes 3 and 6, LMP-1 antisense-treated. The 113-kD PARP and its 89-kD cleavage product are indicated (arrows).