Effect of cyclin d1 and Id1 on EMT markers. MDA-MB-231 cells were monitored 20 h post-transfection with the indicated siRNA (cyclin D1/CDK4/6/Id1) or vector (Id1) for changes in EMT-related gene expression by microarray analysis. Additionally, MDA-MB-231 and ZR75-1 gene expression was examined by qPCR assay. Plots are mean values from at least three independent experiments Error bars represent standard deviation. (A) Microarray analysis of SNAI1, SNAI2, CDH11, TWIST1 and VIM gene expression. (B-D) CCND1, ID1 and SNAI2 in MDA-MB-231 cells. (E, F) qPCR analysis of CCND1 and SNAI2 in ZR75-1 cells. ***P ≥ 0.001, **P ≥ 0.01, *P ≥ 0.05 vs. control, two-tailed student's t-test.