Fig. 3.

TGF-β downregulates TβRIII in human glioma cell lines. a RT-PCR analysis of TβRIII mRNA expression in human LTC (LN-18, LN-428, LN-319, A172, U87MG, T98G, LN-308, LN-229), GIC (T-325, T-269, ZH-161, S-24, ZH-305), and hCMEC normalized to Arf1. b TβRIII protein levels in total cell lysates were examined by immunoblot, and actin was used as a loading control. c Cell surface TβRIII protein levels were assessed by flow cytometry in LN-229 cells, HUVEC cells were measured as positive control. Protein levels are expressed as mean specific fluorescence index (SFI). d Shed TβRIII levels normalized to the total cell number of the respective supernatants were determined by ELISA. A transient knockdown of TβRIII in LN-229 cells was included as a negative control. e Relative changes of TβRIII mRNA expression in LN-229 cells were assessed after exposure to TGF-β2 (2 or 10 ng/ml) or to SD-208 (5 µM) for 24 h. Expression ratios relative to the respective control are depicted. f TβRIII protein levels in whole cell lysates of LN-229 cells were detected by immunoblot following the treatments described in e. g and h Shed TβRIII levels in LN-229 glioma cell supernatants following the treatments as described in e were determined by ELISA (g) and by immunoblot (h), ponceau S staining is shown as loading control in h