Effects of recombinant hIFN-α/β on AML proliferation and cell signaling. (A) ³H-thymidine uptake assay showing a linear reduction in proliferation with an increasing dose of hIFN-α (dashed line) or hIFN-β (solid line) following stimulation of AML cell lines in vitro for 3 days. (B) Western blot of HL-60 cells showing phosphorylation of JAK-1 and STAT-1 in response to hIFN-β stimulation at time points of 0, 10, 30, and 60 minutes.