FIGURE 1.

PP242 activates ERK. In A, 8226 or MM1.S cells were exposed to increasing concentrations (in nm) of rapamycin (rap) or pp242 for 30 min, after which immunoblot assay was performed. Fold increase, determined as described under “Experimental Procedures” is mean of four independent experiments. *, significantly greater than control, non-treated cells, p < 0.05; In B, MM cells treated with DMSO (control), rapamycin (250 nm), pp242 (250 nm) or IL-6 (100 units/ml) for 30 min, after which phos-ERK was immunoprecipitated and tested for its ability to phosphorylate ELK-1 shown by immunoblotting with anti-phospho-ELK-1 antibody. In C, 3 separate primary MM samples treated as shown ± pp242 (in nm) with immunoblot for phospho-ERK (P-ERK) and total ERK (T-ERK). Fold increase in ERK phosphorylation is from a single experiment from each of the 3 patient samples. Patient 2 specimen treated ± 500 nm pp242 for 1 or 3 h.