Ab96621

Total proteins were extracted using RIPA buffer (50 mM Tris (pH 7.4), 1 mM EDTA, 150 mM NaCl, 1% NP-40, 0.5% sodium deoxycholate) supplemental with protease inhibitors (Roche). Western blot assay was performed as previously described^{28 (link)} with antibodies against DDX39 (ab96621, Abcam), TCF4 (#2596, Cell Signaling Technology), LEF1 (#2230, Cell Signaling Technology) and GAPDH (G8795, Sigma). For nuclear proteins extraction, KeyGEN Nuclear and Cytoplasmic Protein Extraction Kit (KGP150, KeyGEN BioTECH) was used, the antibodies against β-catenin (#8480, Cell Signaling Technology) and EF-1α (#2551, Cell Signaling Technology) were used.

The mouse monoclonal antibody against ECD was previously described (31 (link), 39 (link)). The antibodies used in these studies include those against PRPF8 (ab79237), DDX39A (ab96621), LRPPRC (ab97505), and ALY (ab202894) and were from Abcam. Antibodies against CRM1 (46249) and ErbB2 (2242S) were purchased from Cell Signaling. For immunofluorescence staining, we used anti-ECD (catalog number  HPA006465; Sigma-Aldrich) and anti-DDX39 (catalog no. sc-271395; Santa Cruz Biotechnology) antibodies; secondary antibodies tagged with Alexa Fluor 488 (A32731 and A32723) and Alexa Fluor 568 (A-11011 and A-11031) and anti-FLAG antibody (F3165) were from Sigma-Aldrich.