Fig. 3. IGFBP-5 and IGFBP-3 reverse IGF-I mediated suppression of apoptosis in primary mammary epithelial cells. Following serum-starvation, cells were either treated with (A) 1-10 nM IGFBP-5 or (B) 1-10 nM IGFBP-3 alone or in combination with 1 nM IGF-I. FCS and SFM indicate cells maintained in serum-containing and serum-free growth medium, respectively. The number of apoptotic cells was determined using Hoechst 33258 staining and counting of cells with typically apoptotic nuclear morphology. Data are means±s.d. from three independent experiments.