Zhang et al. BMC Cancer 2011, 11:32 http://www.biomedcentral.com/1471-2407/11/32 Page 5 of 12 Figure 1 Immunohistochemical analysis of RRIG1 expression. Breast tissue sections were immunostained with the rabbit polyclonal anti- RRIG1 antibody. DCIS, ductal carcinoma in situ. expression of different genes, indicating that different breast cancer cell lines may have different gene alterations and that RRIG1 can regulate expression of some of them for control of breast cancer cell proliferation, migration, and invasion. Furthermore, we confirmed that RRIG1 was able to suppress RhoA activity, whereas antisense RRIG1 promoted RhoA activity in these breast cancer cells (Figure 4C). Because a recent study reported that the MDA-MB-435 cell line may have originated from mela- noma cells [10,11], we added another RRIG1-positive cell line for antisense RRIG1 transfection. Antisense RRIG1 cDNA reduced RRIG1 mRNA levels but did not affect expression of SH3 domain GRB2-like endophilin B2 (SH3GLB2) (Figure 5). Knockdown of RRIG1 expression enhanced cell viability and invasion capacity of T47D cells (Figure 5).