Peg-Arg I induces T-ALL apoptosis. (A) CCRF-CEM cells were cultured in medium with or without peg-Arg I and the expression of annexin V was tested after 24, 48, 72, and 96 hours by flow cytometry. (B) Malignant T-cell lines including CCRF-CEM, Molt-3, Molt-4, and Jurkat were cultured as in panel A and tested for the expression of annexin V after 72 hours. Peg-Arg I impaired the mitochondrial membrane potential (C), and induced active caspase-3 expression (D) in CCRF-CEM cells. Values are from 3 similar experiments.