IGF1 and breast cancer: We then assessed the effect of selected paracrine growth factors known to be secreted by breast cancer cells, to be binding partners of decorin and to have an already shown paracrine action on syndecan-1 (i.e., PDGF, bFGF, EGF, IGF-I and TGF-β) [19,35,89,90] on the transcriptional regulation of decorin in human breast stromal fibroblasts.