The synergistic cytotoxicity of 15d-PGJ2 and VP-16 on the proliferation of Caki-2 cells was not associated with PPARγ. The cells were assayed for viability using the MTT assay following treatment with VP-16 alone (70 μM) (open circles) and with the combination of VP-16 (70 μM), 15d-PGJ2 (20 μM) and GW9662 (0, 0.1, 0.5, 1, 5, 10 and 50 μM) (closed triangles) for 24 h. The results are expressed as means ± standard error of the mean of three independent experiments. 15d-PGJ2, 15-deoxy-Δ12,14-prostaglandin J2; VP-16, etoposide.