C-terminal HSP90 inhibitors reduce total FN levels in fibroblasts and breast cancer cells. (A) Schematic diagram showing the HSP90 domains targeted by inhibitors (NBD: N-terminal nucleotide-binding domain; MD: middle domain; CTD: C-terminal domain). Treatment of MEF-1 and Hs578T breast carcinoma cell lines with increasing concentrations of the (B) N-terminal HSP90 inhibitor, 17-dimethylamino-ethylamino-17-demethoxydeldanamycin (17-DMAG) or (C) C-terminal HSP90 inhibitors, novobiocin (NOV) or coumermycin A1 (CA1). Levels of FN in whole cell lysates were determined by western blot and average densitometry (±SD, n = 3) using ImageJ. Images are representative of triplicate experiments. Statistical significance was determined using a one-way ANOVA and Bonferroni post-test in GraphPad Prism 4 (* p < 0.05, ** p < 0.01, ns = not significant).