Cluster analysis of the differentially expressed genes using TMEV software. The 993 genes in Additional file 1 are clustered on the basis of the log2 expression ratio. Up-regulated and down-regulated genes are colored in red and green, respectively. Columns refer to the seven experiments performed using different TGFβ1 concentrations (5–10–50 ng/ml) and substrates (collagen type I and plastic). Note that genes are grouped in large blocks, in which they tend to be up- or down-regulated in all the first six experiments.