Zhang et al. BMC Cancer 2011, 11:32 http://www.biomedcentral.com/1471-2407/11/32 Page 10 of 12 Figure 5 The effects of antisense RRIG1 in breast cancer T47D cells. All experiments were repeated at least once with similar results. A, Semiquantitative RT-PCR. The gene-transfected cells were grown in G418-containing medium for 5 days, and RNA was then isolated from the cells and subjected to semiquantitative RT-PCR analysis of RRIG1, SH3GLB2, and GAPDH expression. B, MTT assay. The gene-transfected cells were grown in G418-containing medium for 1 or 5 days, and cell viability was measured using the MTT assay. C, Invasion assay. These gene- transfected breast cancer cells were grown in G418-containing medium and then subjected to the cell invasion assay in Boyden chambers with Matrigel for 48 h. The invaded cells were stained with 1% crystal violet solution and then counted and summarized. Vec, vector-only; AS, antisense RRIG1 cDNA; *p < 0.05 vs. the control. suppressed cell proliferation, invasion, and angiogenesis in vitro and in vivo [27-31]. The RRIG1 protein can bind to the RhoA protein, although it is unknown whether this binding is direct or indirect [5]. We studied the RRIG1 and RhoA association because, in our unpub- lished findings of an in vitro pull-down assay, RRIG1 protein was able to pull down RhoA protein. Conclusion Our current study clearly showed the importance of lower RRIG1 expression in breast cancer cell growth, colony formation, invasion, and altered gene expression. Future study will attempt to determine the underlying molecular mechanisms and define RRIG1 as a tumor- suppressor gene in breast cancer.