β2 integrins induce proliferation of AML cells by the activation of Syk. (A-E) Shown are growth curves of FFM05 and FFM12 cells that were treated with shRNAs against (A) Mac-1, (C) CD18, and (E) FcRγ (all shown as gray lines) or the respective control shRNAs (black lines). The shRNA-treated FFM05/12 cells were cultured on confluent layers of KM-102 bone marrow–derived stroma cells. Proliferation was monitored by XTT-based assay. After 48 hours of AML/stroma cell coculture, FFM05/12 cells were harvested, and lysates of FFM05 and FFM12 cells that were treated with (B, D, F) control shRNAs (lane 1) or (B) Mac-1–, (D) CD18-, or (F) FcRγ-specific shRNAs (all shown in lane 2) were subjected to immunoblot analyses using antibodies against Mac-1, CD18, FcRγ, pSTAT3, pSTAT5, pSyk, and actin.
