TGFB1 and Patent ductus arteriosus: On the other hand, HPAFII treated with control siRNA had high levels of phosphorylated JNK and c-Myc with TGF-β exposure, but when MUC1 was downregulated using a specific siRNA, the phosphorylation of JNK and c-Myc were significantly reduced (Figure 3B), thus, TGF-β destabilized c-Myc when MUC1 expression is low in PDA cells (Figure 3C).