Background
Insulin-like growth factors (IGFs) regulate normal growth and development. In breast cancer, they stimulate cell proliferation, cell migration and inhibit apoptosis. The IGF signal transduction pathway is, therefore, a potential therapeutic target in the treatment of breast cancer [1, 2]. Inhibitors of the IGF pathway may be effective in the treatment of breast cancer with de novo or acquired endocrine resistance. We have studied IGF signalling in oestrogen nonresponsive MDA-MB-231, HBL-100 and BT-20 breast cancer cell lines as models of endocrine resistant breast cancer. Oestrogen responsive MCF-7 cells were also studied.