(A) C646 has a more potent effect on cell growth than Lys-CoA-Tat does. Cells were treated for 24 h and proliferation was measured via 3H-thymidine incorporation pre- and post-treatment. Data for each cell line were normalized to 3H counts measured pre-treatment. C37 is an inactive derivative of C646. DMSO serves as a vehicle control for C37 and C646. Ac-DDDD-Tat is a control peptide for Lys-CoA-Tat. WM35, WM983A, and 1205Lu are melanoma cell lines representing three stages of cancer progression: radial, vertical, and metastatic, respectively. (B) Two out of three non-small cell lung adenocarcinoma cell lines demonstrate significant growth inhibition after treating with C646 and Lys-CoA-Tat for 24 h. (C) C646 does not have a significant inhibitory effect on NIH3T3 cell proliferation.