Sca-1 regulates TGFβ signaling in proximal renal tubule cells.

<p>(A) Western blots from a representative experiment, one of three conducted, showing phospho-Smad3 (p-Smad3) in untreated cell lysates from serum-starved control and Sca-1 silenced D5 and C8 cells and after exposure to TGFβ₁ for 15 or 30 min. Smad2/3 detection served as a loading control. (B) Blocking TβRI activity abrogates ectopic Smad3 activation in Sca-1 silenced cells. TKPTS or Sca-1 silenced cells (D5) were serum starved and pretreated with SB431542 for 30 minutes prior to addition of TGFβ₁. Cell lysates were analyzed by Western blot for detection of p-Smad3, with Smad2/3 used to control for protein loading. (C) Histograms (mean<u>+</u>sd, n = 3) showing <i>Pai-1</i> mRNA levels in TKPTS, D5, and C8 cells at baseline and following treatment with TGFβ₁ and/or SB431542.