RalB rather than RalA mediates SDF-1–induced MM cell migration. (A) Lysates of OPM-1 and NCI-H929 MM cells co-transfected with GFP and shRenilla, shRalA, or shRalB were immunoblotted to determine RalA and RalB expression. Actin served as a loading control. (B) OPM-1 and NCI-H929 MM cells co-transfected with GFP and shRenilla, shRalA, or shRalB were allowed to migrate for 4 hours in the absence (c) or presence of 100 ng/mL SDF-1 (SDF-1) in Transwells. The migration of the shRenilla-transfected GFP-positive cells in the presence of SDF-1 was normalized to 100%, and shown as the mean ± SD of triplicates (*P < .05). The results are representative of at least 2 independent experiments.