A, Representative p27 IB (left) shows significant p27 protein expression decrease in MMTV-ζ.neu tumors compared to MMTV-neu. Protein quantification is relative to β-actin (right). B, 14-3-3-ζ overexpressing cells showed significant decrease in p27 protein by IB. C, 14-3-3ζ knockdown in MCF7 cells rescued p27 protein expression by IB. D, miR-221 expression was increased in 14-3-3-ζ overexpressing cells versus control cells by qRT-PCR. E, 14-3-3ζ knockdown in MCF7 cells led to decreased miR-221 expression analyzed by qRT-PCR. F, AntagomiR-221 rescued p27 protein expression in MCF7-ζ cells by IB. G, Pre-miR-221 overexpression decreased p27 protein in MCF7 cells with 14-3-3ζ knockdown. H, qRT-PCR shows significant increase in miR-221 in MMTV-ζ.neu mammary tumors compared to MMTV-neu (all n=5).