Effect of cucurbitacin B on the level of nucleophosmin/B23, STAT3, tubulin, and c-Myc expression. MCF-7 and MDA-MB-231 were treated with 0, 2.5, and 5 μM cucurbitacin B for 48 hr. A. RNA was extracted for real-time RT-PCR to quantitate the gene expression levels of nucleophosmin/B23, STAT3, tubulin, and c-Myc after cucurbitacin B treatment. Results shown are the average of three independent experiments. *, P < 0.05 (treated vs untreated control) B. Western blot was analyzed for protein expression. GAPDH was used as loading control.