Fig. 4

Activin A facilitates TGFβ1-induced type II receptor expression without altering TGFβ1 receptor sensitivity in MC. a TGFβ1 for 30 min increased TRII expression and Smad3 activation in whole cell lysate, and both were prevented by 24 h pretreatment with follistatin (n = 6). b There was no change in TRII transcript after 24 h of follistatin with or without TGFβ1 for 30 min. c Pretreatment with an actA neutralizing antibody for 24 h inhibited acute (30 min) TGFβ1-induced Smad3 activation and TRII upregulation (n = 6–7). These were similarly inhibited by downregulation of the actA type I receptor ALK4 with siRNA (d) (n = 3). e Pretreatment with actA (20 ng/ml) for 24 h did not affect acute TGFβ1-induced Smad3 activation (n = 6). *, **, ****P < 0.05, 0.01, 0.0001; one-way ANOVA with Tukey’s multiple comparisons post hoc test