STAT3 and familial pancreatic carcinoma: In contrast to PAO-induced inhibition of nuclear Stat3 DNA-binding activity induced by EGF [6], immunoblotting analysis showed treatment with PAO has no effect on the nuclear presence of EGFR, Src and Stat3 heterocomplex in pancreatic cancer cells (Fig. 3D), suggesting the nuclear presence of the heteromeric complex is not dependent on endocytosis.