Rac1 knockdown induces apoptosis in human lymphoma cells. (A) BL41 cells were transduced with either a YFP-tagged shRac1 construct or scrambled sh control (shSCR) and sorted 48 hours after infection. Cells were harvested 24 hours after sorting and immunoblotted with antibodies to Rac1, Rac2, pan-Rac, pPAK1, cleaved caspase-3, cytochrome c, and Gapdh. (B) Cells from panel A were analyzed by flow cytometry to determine the Annexin V/ 7AAD-positive population. Error bars represent SD.