Effect of PlGF dose on the secretion of chemokines from THP-1 cells. THP-1 cells (1 × 10⁶/mL) were treated with PlGF (25 to 250 ng/mL) for time periods of 1 and 4 hours. The supernatant was collected and (A) MIP-1β, (B) MCP-1, and (C) IL-8 levels quantified as indicated in Figure 6. Data are expressed as means ± SD of n = 3.