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. Author manuscript; available in PMC: 2015 Sep 12.
Published in final edited form as: Oncogene. 2014 Mar 31;34(11):1341–1353. doi: 10.1038/onc.2014.72

Figure 4.

Figure 4

Inhibition of Stat3 binding to immobilized phosphopeptide ligand by piperlongumine. Binding of recombinant Stat3 (200 nM) to a Biacore sensor chip coated with a phosphododecapeptide (amino acids surrounding Y1068 within EGFR) was measured in real time by SPR in the absence (0 μM) or presence of piperlongumine (0.1 to 1,000 μM). Panel A shows resonance units as a function of time in seconds. In panel B, the equilibrium binding levels obtained ± piperlongumine were normalized (resonance obtained in the presence of compound ÷ the response obtained in the absence of compound × 100) and plotted against Log [nM] PL and IC50 value calculated.