Strain-induced quantitative mRNA-expression analysis of PDL cells related to MAP-kinase signalling and cell cycle, ECM and integrins, and growth factor pathways. PDL cells were seeded on flexible bottom cell culture dishes and strained with averaged 2.5%. For quantitative mRNA analysis, PDL cells of unstrained controls and cells after 0.5 h strain period were harvested, and RNA was isolated and quantified for pathway-specific analysis. The relative increase and decrease in gene expression were internally normalised versus a quotient of 4 different housekeeping genes, and plotted in the graph. The data represent the mean of three independent experiments, and only significant expression modulations were included in the graph. The respective statistics were considered in the evaluation software. Plotted genes were allocated to a specific pathway and the respective columns were coloured for MAP-kinase signalling and cell cycle in orange, for ECM and integrins in light blue, and for growth factors in green, respectively.