Figure 4

Knockdown of MBNL1 induces precocious TGFβ3 secretion. Stage 14 AVC explants were transfected with or without MBNL1 siRNA. After a boost at 6 hrs, medium was added to the explants. After 12 hrs, the conditioned medium was removed and fresh medium was added. This was repeated twice more, and all supernatants were assayed by ELISA. The mean levels of secreted TGFβ3 are shown as a percentage of the baseline level in the medium + the standard errors of the means. TGFβ3 levels in supernatants conditioned by mock-treated explants did not rise above the baseline level found in M199+ alone until 24–36 hrs after the boost. Supernatants from MBNL1 siRNA-treated explants, however, had increased levels of TGFβ3 within the first 12 hrs after the boost. Levels remained elevated until 36–48 hrs after the boost, when levels were comparable to supernatants from mock-treated explants. An asterisk indicates a significant difference from mock-transfected explants (P ≤ 0.05) at the same time point.