Figure 4.

Tacrolimus induces transforming growth factor-β (TGF-β) receptor activation and downstream Smad2/3 phosphorylation in mouse kidneys. To investigate whether tacrolimus induces TGF-β receptor activation, wild-type C57BL/6 mice were treated with either 10 mg/kg tacrolimus or vehicle (ethanol/DMSO/saline) for 21 days. Mouse kidneys were assessed for total type I TGF-β receptor subunit (TGFβRI) expression via Western blot (A). TGFβRI activation was examined by assessing phospho-TGFβRI expression via both Western blot (B) and immunohistochemistry (C). To assess whether tacrolimus induces downstream TGF-β receptor signaling, phospho-Smad2/3 abundance (D) was assessed via Western blot. Representative images are shown. Values are means ± SE for 7 or 8 animals per group. Statistical tests were conducted using a t test to detect differences between the means of experimental groups. *P < 0.05 and **P < 0.005 vs. vehicle.