Figure 4.

Effect of silencing TGFB1 on rhTGFβ1-induced growth arrest in pancreatic and breast cancer cells with aTGFβ production. (A) Panc1 or MDA-MB-231 cells were transiently transfected with 50 nM of either control (C) siRNA or TGFB1 (T) siRNA and subsequently subjected to treatment with rhTGFβ1 (5 ng/mL) for 50 h. Cells were trypsinized and counted. Data (cell numbers) shown are representative of three assays, with non-rhTGFβ-treated control transfectants set arbitrarily at 100 (mean ± SD, n = 3). (B) Immunoblot analysis of p21^WAF1 in Panc1 or MDA-MB-231 cells transfected as outlined in (A) but treated with rhTGFβ1 for 24 h. The graphs underneath the blots show results from densitometry-based quantification of band intensities (mean ± SD, n = 3). Successful knockdown of TGFB1 in (A,B) was verified by ELISA of secreted TGFβ1. The asterisks (∗) indicate significance (p < 0.05).