IndraLab

"Phosphorylation of Smad3 on serine site 423/425 in the gastrocnemius and soleus did not differ between the two groups of mice. In the whole group, mature myostatin was positively associated with phosphorylation on the Smad2 serine site 423/425 in the soleus (r = 0.47, P < 0.05, not shown) and the gastrocnemius (r = 0.33, P < 0.05, not shown), but not on Smad3 serine site 423/425 (P > 0.22) or the Smad2 linker region (P > 0.30)."

"Western analysis to detect phospho-Smad2/3 revealed that while treatment with RA did not induce C-terminal phosphorylation of either Smad, treatment with TGFβ in the presence or absence of RA resulted in robust phosphorylation of the Smad3 S423 and S425 residues (Figure 2E). These results suggest that the effects of RA on TGFβ-mediated signaling are not due to changes in Smad3 phosphorylation status. However, in cells treated with both TGFβ and RA, we did detect a significant decrease in Smad2 phosphorylation of the equivalent residues without changes in Smad2 levels (Figure 2E), suggesting that RA may interfere with the actions of TGFβ by reducing Smad2 activation by phosphorylation."