Effect of PM on the expression and release of GM-CSF, IL-6 and AREG biomarkers. Ultrafine PM (UF [0.03 μm-0.17 μm]), fine PM (F [0.17 μm-1 μm]) and coarse PM (C [1 μm-10 μm]) were used at 1 to 10 μg.cm-2 for 24 h exposures. The pro-inflammatory cytokines GM-CSF (A) and IL-6 (B) were studied as well as AREG growth factor (C). mRNA were evaluated by RT-qPCR and protein assessed in supernatants by ELISA assay. These data are expressed comparatively to the control (=1). mRNA and protein releases are mean of four replicates. * p < 0.05 compared with the control fixed to 1.