The anti-amylase and anti-β-actin antibodies were from Sigma-Aldrich (St Louis, MO), anti-cytokeratin-19 antibody from Leica Microsystems (Buffalo Grove, IL), anti-claudin-18 antibody from Invitrogen (Carlsbad, CA), anti-Ras antibody from Epitomics (Burlingame, CA), anti-GST and anti-GFP from Santa Cruz (Santa Cruz, CA), anti-activated Notch1 antibody from Abcam (Cambridge, MA), anti-PKD1 from Antibodies-online Inc. (Atlanta, GA), anti-PKD2 from Acris Antibodies (San Diego, CA), anti-PKD3 antibody from Bethyl Laboratories (Montgometry, TX), and anti-pS744/748-PKD antibodies from Cell Signaling Technology (Danvers, MA) or Abcam. Recombinant human TGFα was purchased from Chemicon (Billerica, MA) and R&D Systems (Minneapolis, MN). Dexamethasone was from Sigma-Aldrich, soybean trypsin inhibitor and collagenase I from Affymetrix (Santa Clara, CA). Phenol red-free Matrigel and rat tail collagen I were from BD Biosciences (San Diego, CA). Hoechst 33342 was purchased from Invitrogen (Grand Island, NY). The PKD inhibitor CRT0066101 was from TOCRIS (Ellisville, MO) and kb-NB-142-70 was described previously 51 (link). The γ-secretase inhibitors DAPT and R04929097 were from Cellagen Technology (San Diego, CA).