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. 2001 Sep 15;108(6):851–859. doi: 10.1172/JCI12807

Figure 1.

Figure 1

MEK blockade inhibits the growth of leukemic, but not normal, hematopoietic cells. (a) AML cell lines were assessed for MAPK phosphorylation by Western blot. (b) OCI-AML3 cells were exposed to DMSO (C) or PD98059 at the indicated doses for 6 hours. MAPK phosphorylation was then assessed by Western blot. (c) OCI-AML3 cells were treated as in b. MAPK enzymatic activity was measured by the ability to phosphorylate the specific substrate Elk1 in an in vitro kinase assay. (d) Mononuclear cells from patients 5 (filled circles), 9 (open squares), 10 (filled triangles), and 11 (open circles) were grown in colony assays in the presence of DMSO or PD98059 at the indicated doses. Results show AML blast colonies in the PD98059-treated group, expressed as a percentage of the colonies in the DMSO-treated group, and represent the average of quadruplicate cultures (SEM was constantly less than 10%). (e) MACS-sorted CD34+ cells from healthy donors were cultured in the presence of DMSO or 20 μM PD98059. Viability was then assessed by trypan blue dye exclusion. Results show viable cells in the PD98059-treated group, expressed as a percentage of the viable cells in the DMSO-treated group (four bars at left; each bar represents a single donor). Bone marrow cells from healthy donors were grown in colony assays in the presence of DMSO or 50 μM PD98059. Results show CFU-GM and burst-forming units–erythroid (BRU-E) in the PD98059-treated group, expressed as a percentage of the colonies in the DMSO-treated group (four bars at right; two donors).