Fig. 7.

Effect of inhibition or knockdown of EGFR on signal transducers and activators of transcription 3 (STAT3) activation and the effect of S3I-201 on RPTC proliferation. RPTCs were cultured in the DMEM with 5% FBS for 48 h in the absence or presence of gefitinib (100–500 nM; A) or transfected with scrambled siRNA or specific siRNA to EGFR (B) or STAT3 (E and F) and incubated for 48 h in the same medium. Cells were harvested and cell lysates were subjected to immunoblot analysis with antibodies to p-STAT3, STAT3, and GAPDH or α-tubulin. Representative immunoblots from 3 or more experiments are shown (A and B). RPTCs were cultured in the DMEM with 5% FBS for 48 h in the absence or presence of S3I-201 (100 and 200 μM). Cells were harvested and cell lysates were subjected to immunoblot analysis with antibodies to p-STAT3, STAT3, PCNA, and α-tubulin. Representative immunoblots from three or more experiments are shown (C and E). Cell proliferation was determined by counting cell numbers (D and F). Means with different superscript letters are represented as significant difference from one another (P < 0.05).