Effects of insulin-like growth-1 (IGF-I) stimulation on primary breast fibroblasts and CCL-171 fibroblasts. (A) Unsupervised hierarchical clustering of genes differentially expressed in fibroblasts upon IGF-stimulation. Unsupervised hierarchical clustering of genes differentially expressed between IGF-I stimulated and non-stimulated primary breast fibroblasts as discovered by SAM (genes with a false discovery rate ≤ 0.05% are represented). Grey fields indicate missing expression values. The colour of dendrogram branches renders information about sample stimulation; yellow = not stimulated and blue = stimulated with IGF-I (50 ng/mL). (B) IGF-I induced proliferation of CCL-171 cells. Cell proliferation assay based on absorbance measurement of WST-1. Formazan absorbance correlates to the cell number. Average absolute absorbance of replicates of CCL-171 cells stimulated with 50 ng/mL IGF-I in comparison to non-stimulated cells at different time points. Points represent the average of six replicates per condition and correspond to the cell number. The vertical error bars denote the standard deviation. Stimulation of CCL-171 cells with IGF-I induces significant, constant cell growth after 24, 48 and 72 h. (C) IGF-I induced proliferation of primary breast fibroblasts. Cell proliferation assay based on absorbance measurement of WST-1. Points represent the average absolute absorbance of a minimum of eight replicates of six primary fibroblasts (carcinoma associated fibroblasts and normal fibroblasts) after 24, 48 and 72 h. Error bars correspond to the magnitude of the standard deviation. Stimulation of primary breast fibroblasts with IGF-I induces significant, constant cell growth.