Activated monocytes do not induce proliferation in ECs. (A) Monocytes activated with TNFα, IL-1β, or LPS or by previous interaction with ECs lose their mitogenic potential as measured by ³H-thymidine incorporation. (B) HGF levels in the medium spiked 15 minutes and again 60 minutes after interaction of unactivated monocytes with subconfluent HUVECs. M indicates monocytes; H, HUVECs; PBMC, peripheral blood mononuclear cells; LPS, lipopolysaccharides; IL, interleukin; and EGM, endothelial growth medium (n ≥ 3, *P < .001).