IGFBP3 and breast cancer: However, the subset of breast cancer cell lines in which IGFBP-3 was downregulated could be grouped by the level of IGFBP-3 expressed prior to treatment, with a decrease in IGFBP-3 expression in response to etoposide or doxorubicin occurring in those lines with the highest basal level of IGFBP-3 expression.