Cardiac glycoside family members inhibit the FA/BRCA pathway.

<p>(A) U2OS cells were pretreated with the indicated concentration of digitoxin or digoxin for 1 h and then incubated in 200 ng/ml MMC for 24 h. After incubation, the cells were fixed and processed for FANCD2 immunofluorescence and the FANCD2 foci were analyzed with IN Cell Analyzer. Representative graphs from three independent experiments are shown. Values represent the means ± SEM.(B) (C) Protein extracts from U2OS cells pretreated with 5 µM curcumin, 100 nM ouabain, 100 nM digitoxin and 100 nM digoxin and incubated in 200 ng/ml MMC for 24 h as described in (A) were analyzed by Western blotting using antibodies against (B) FANCD2, (C) FANCI, and β-actin. L/S values shown represent the ratio of FANCD2 (L)/FANCD2 (S) or FANCI (L)/FANCI (S).