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Fig. 7. Resistance of dominant active STAT3 transfectants to the EGFR autocrine axis. A, representative MTT assay demonstrating growth stimulation of vector control transfectants relative to untreated control cells, compared with STAT3-C-transfected cells treated with exogenous EGFR ligand (EGF, 30 ng/ml). The experiment was repeated three times with 3 wells/condition for each experiment. B, representative MTT assay demonstrating relative growth inhibition of control-transfected cells compared with STAT3-C transfectants treated with an EGFR-specific tyrosine kinase inhibitor at either of two doses ({square}, 100 nM PD153035; , 1000 nM PD153035).