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. 2013 Nov;27(11):4444–4454. doi: 10.1096/fj.12-224907

Figure 1.

Figure 1.

TGFβ induces ErbB signaling via autocrine activation of the PDGFR pathway. A) RT-PCR analyses of ErbB ligands (12 h post-treatment) and Western blot analysis of ErbB1 phosphorylation (15 h) following cell stimulation with TGFβ1 in the presence of the PDGFR inhibitor AG1295. The profile of PDGFR phosphorylation (12 h) confirms the efficacy of AG1295, whereas that of Smad3 (3 h) proves its specificity. B) RT-PCR analyses of ErbB ligands (12 h post-treatment) upon TGFβ1 stimulation of cells transduced with shRNA targeting PDGFRα, PDGFRβ, or both (shRα+shRβ). NT denotes nontargeting control. Western blot analyses show consistent Smad3 phosphorylation and efficient knockdown of PDGFRα and PDGFRβ (3 h). The data presented further corroborate the role of PDGFR in mediating up-regulation of ErbB ligands by TGFβ. C) Time course of ErbB ligand induction by PDGF in AKR-2B cells. RT-PCR analyses of ErbB ligands show a fairly rapid up-regulation of ErbB ligands by PDGF isoforms, with isoforms containing the B chain being the most potent.