Figure 5

Effects of zoledronic acid on follistatin secretion and follistatin:activin ratio. MDA-MB-231 (A) and MCF7 (C) cells were treated with medium alone, 25 μM or 50 μM ZOL for 48 hours and levels of secreted activin and follistatin measured by ELISA. Molar ratio of follistatin:activin (B + D) was calculated by converting mean quantity of secreted protein per million cells (pg/ml) to pmol/l by dividing by the molecular weight of each protein, and then expressed as a ratio. A molar ratio of 4 (dashed line) represents the level at which activin is neutralised by follistatin: an excess of follistatin:activin increases tumour growth (above dashed line). Data represents mean + SEM of 3 replicates and 3 repeats, *= p value <0.05, NS not significant.