Figure 2.

Cell proliferation induced by foetal bovine serum (FBS) and platelet‐derived growth factor‐BB (PDGF‐BB). Cells were seeded with DMEM‐F12 containing 10% FBS at 2000 cells/cm² in 24‐well plates (for cell counts) or 96‐well plates (for MTT assay). (a) At day 3 of culture, cells were incubated in supplemented DMEM‐F12 with or without 10% FBS until day 7 and media were refreshed at day 5. Counts were performed in triplicate on trypsinized cells from 4 to 6 separate cultures and data are mean ± SEM (two‐way anova; P < 0.004). (b) After 4 days of culture, cells were serum‐starved for 24 h and were incubated for 48 h in DMEM‐F12 without FBS and with increasing concentrations of PDGF‐BB. Cell proliferation was determined by MTT assay and data are expressed as the mean ± SEM of percentage of control conditions without growth factors from four individual experiments (anova; P < 0.0001, Dunnett's t‐test; P < 0.01 from 7.5 ng/mL).