Induction of tyrosine phosphorylation after stimulation with anti-CD34 MoAbs. (A) FACS analysis of KG1a cells stained with the anti-CD34 MoAbs used in this study. Cells were stained with MOPC21 (a, control IgG), My10 (b, class I MoAb), 4A1 (c, class II MoAb), QBEND10 (d, class II MoAb), and 8G12 (e, class III MoAb). Solid lines represent staining with specific antibodies, and dotted lines represent staining with the secondary reagent alone. (B) Western blot of equal amounts of Triton X-100 lysates from KG1a cells stimulated for 30 minutes with anti-CD34 MoAbs (lanes 2 through 5) or MOPC21 as a control (lane 1) as described in Materials and Methods, probed with anti-pTyr (4G10, top), and reprobed with anti-CD34 (4A1, bottom). Molecular size markers are indicated on the left (kD).