Effects of PPP on IGF-1–induced DNA synthesis and VEGF secretion. The 5T33MM cells were stimulated with or without 10 ng/mL IGF-1 (DNA synthesis) and 100 ng/mL (ELISA) after a 30-minute incubation with 1 μM PPP (▪) or not (□). DNA synthesis (A) was measured by a thymidine incorporation assay and VEGF secretion (B) by ELISA. Results are shown relative to unstimulated cells. The maximum IGF-1–stimulated VEGF secretion reaches 250 pg/mL. Mean values ± SD for 3 independent experiments are shown.*P < .02; **P < .05.