Martelli A, Cappellini A, Tazzari P, Billi A, Tassi C, Ricci F, Fala F, Conte R. Caspase-9 is the upstream caspase activated by 8-methoxypsoralen and ultraviolet-A radiation treatment of Jurkat T leukemia cells and normal T lymphocytes. Haematologica 2004; 89(4):471-479.