We show that forced expression of OGR1 attenuated MCF7 breast cancer cell migration in vitro. We also present the first evidence that these effects were mediated by the ability of OGR1 to interact with Gα12/13 and modulate the small GTPase Rho, which then suppressed the activation of Rac1 that ultimately inhibited cell migration. This evidence concerns the gene RHO and breast carcinoma.